t = int(input())
for _ in range(t):
    a, b = map(int, input().split())
    if b >= a:
        print(-1)
    else:
        print(min(b, a - b))

t = int(input())
for _ in range(t):
    s = input()
    ans = 1
    if "010" in s or "101" in s:
        ans += 1
    if "000" in s or "111" in s:
        ans += 1
    print(ans)

t = int(input())
for _ in range(t):
    n, k = map(int, input().split())
    a = list(map(int, input().split()))
    
    p = [0 for i in range(n+1)]
    for i in range(n):
        p[i+1] = (p[i]+a[i]) % k

    ans = 0
    cnt = [0 for i in range(k)]
    for i in range(k+1, n+1):
        cnt[p[i-k-1]] += 1
        ans += cnt[p[i]]

    print(ans)

#include<bits/stdc++.h>

using namespace std;

void solve()
{
    int n, m;
    cin >> n >> m;
    vector<int> d(n);
    for(int i = 0; i < m; i++)
    {
        int x, y;
        cin >> x >> y;
        x--;
        y--;
        d[x]++;
        d[y]++;
    }
    sort(d.begin(), d.end());
    if(d[0] == 0)
        cout << "Brain Melt\n";
    else if(d[n - 1] == n - 1 && d[n - 2] == 1)
        cout << 2 << "\n";
    else
        cout << "Many\n";
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int t;
    cin >> t;
    for(int i = 0; i < t; i++)
        solve();
}

#include <bits/stdc++.h>

using namespace std;

int t;

int main() {
    const string s25 = "2025", s26 = "2026";
    
    cin >> t;
    for (int tc = 0; tc < t; ++tc) {
        int n;
        string s;
        cin >> n >> s;
        
        vector <vector <int>> nxt(n, vector <int> (10));
        vector <int> cur(10, n);
        
        for (int i = n - 1; i >= 0; --i) {
            cur[s[i] - '0'] = i;
            for (int j = 0; j < 10; ++j)
                nxt[i][j] = cur[j];
        }
        
        vector <int> d(n + 1);
        vector <int> dd(n + 1);
        
        for (int l = 0; l < n; ++l) {
            int r25 = l, r26 = l;
            int i25 = 0, i26 = 0;
            
            while(i25 < s25.size() && r25 < n) {
                int x = s25[i25++] - '0';
                r25 = nxt[r25][x];
            }
            
            while(i26 < s26.size() && r26 < n) {
                int x = s26[i26++] - '0';
                r26 = nxt[r26][x];
            }
            
            int cnt = n - l;
            d[l] += cnt;
            --dd[l + 1];
            
            if (r25 < r26) {
                // bad == [r25..r26-1]
                cnt = r26 - r25;
                d[l] -= cnt;
                ++dd[r25 + 1];
                //--dd[r26];
                if(r26 < n)
                    --dd[r26 + 1];
            }
        }
        
        vector <int> ans(n);
        long long sum = 0, add = 0;
        for (int i = 0; i < n; ++i) {
            sum += d[i];
            add += dd[i];
            sum += add;
            cout << sum << ' ';
        }
        cout << endl;
    }
    return 0;
}

#include<bits/stdc++.h>

using namespace std;

const int INF = 1e9;

void upd(int& x, int y)
{
    if(x > y) x = y;
}

void solve()
{
    int n, k;
    cin >> n >> k;
    vector<int> p(n);
    for(int i = 0; i < n; i++)
    {
        cin >> p[i];
        p[i]--;
    }

    vector<bool> used(n);
    vector<int> len;
    for(int i = 0; i < n; i++)
    {
        if(!used[i])
        {
            used[i] = true;
            int cur_len = 1;
            int j = p[i];
            while(!used[j])
            {
                used[j] = true;
                cur_len++;
                j = p[j];
            }
            len.push_back(cur_len);
        }
    }
    sort(len.begin(), len.end());
    reverse(len.begin(), len.end());

    if(k == 1)
    {
        if(len[0] >= 3)
            cout << "Bob\n";
        else if(len[0] == 1 || n % 2 == 1)
            cout << "Alice\n";
        else 
            cout << "Bob\n";        
    }
    else if(len[0] > k + 1)
    {
        cout << "Bob\n";
    }
    else if(len[0] == k + 1)
    {
        if(len.size() > 1 && len[1] == k + 1)
        {
            cout << "Bob\n";
        }
        else
        {
            int must_remove = 0;
            int cnt1 = 0;
            for(int i = 1; i < len.size(); i++)
            {
                if(len[i] > 1)
                    must_remove += len[i];
                else cnt1++;
            }
            int alice_move = must_remove + cnt1 % (k + 1);
            if(alice_move > k || alice_move == 0)
                cout << "Bob\n";
            else
                cout << "Alice\n";
        }
    }
    else
    {                        
        int m = len.size();
        m = min(m, 2 * k);
        vector<vector<vector<int>>> dp(m+1, vector<vector<int>>(k+1, vector<int>(k + 1, INF)));
        dp[0][0][0] = 0;
        for(int i = 0; i < m; i++)
            for(int j = 0; j <= k; j++)
                for(int c = 0; c <= k; c++)
                {
                    if(dp[i][j][c] == INF) continue;
                    bool alice_can = (j + len[i] <= k);
                    bool bob_can = (i - c < k);
                    if(alice_can)
                        upd(dp[i+1][j + len[i]][c + 1], dp[i][j][c]);
                    upd(dp[i+1][j][c], dp[i][j][c] + (bob_can ? len[i] - 1 : 0));
                }
        bool alice_win = false;
        for(int j = 0; j <= k; j++)
            for(int c = 0; c <= k; c++)
                if(dp[m][j][c] <= k)
                    alice_win = true;

        if(alice_win)
            cout << "Alice\n";
        else
            cout << "Bob\n";
    }
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int t;
    cin >> t;
    for(int i = 0; i < t; i++)
        solve();
}

#include<bits/stdc++.h>

using namespace std;

const int MOD = 998244353;
const int N = 5005;

int add(int x, int y)
{
    x += y;
    while(x >= MOD) x -= MOD;
    while(x < 0) x += MOD;
    return x;
}

int mul(int x, int y)
{
    return (x * 1ll * y) % MOD;
}

int sub(int x, int y)
{
    return add(x, -y);
}

int binpow(int x, int y)
{
    int z = 1;
    while(y)
    {
        if(y & 1) z = mul(z, x);
        x = mul(x, x);
        y >>= 1;
    }
    return z;
}

int fact[N];
int inv[N];

void precalc()
{
    fact[0] = 1;
    for(int i = 1; i < N; i++)
        fact[i] = mul(i, fact[i - 1]);    
    for(int i = 0; i < N; i++)
        inv[i] = binpow(i, MOD - 2);
}

struct Blocks
{
    int n;
    vector<int> cutoff_pos;
    vector<int> pref;
    vector<int> pref_G;
    vector<pair<int, int>> a;

    void rebuild()
    {
        pref = { 0 };
        pref_G = { 0 };
        vector<bool> used(n);
        vector<pair<int, int>> b;
        cutoff_pos = vector<int>(n, -1);
        int sign = 1;
        int cnt = n - 1;
        for(int i = 0; i < a.size(); i++)
        {
            int x = a[i].first;
            int len = a[i].second;
            if(used[x])
                break;
            used[x] = true;
            b.push_back(make_pair(x, len));
            cutoff_pos[x] = i;
            int c = mul(sign, mul(len, fact[cnt]));
            int c_G = mul(sign, mul(len, fact[cnt - 1]));
            --cnt;
            sign = sub(0, sign);
            pref.push_back(add(pref.back(), c));
            pref_G.push_back(add(pref_G.back(), c_G));
        }

        a = b;
    }

    int getF()
    {
        return pref.back();
    }

    int getG(int x)
    {
        if(cutoff_pos[x] == -1) return pref_G.back();
        else return pref_G[cutoff_pos[x]];
    }

    void append(int x)
    {
        if(a.empty() || a[0].first != x)
            a.insert(a.begin(), make_pair(x, 0));
        a[0].second++;
        rebuild();
    }

    Blocks(int n = 0) : n(n) {};
};

void solve()
{
    int n;
    cin >> n;
    vector<int> a(n - 1);
    for(int i = 0; i < n - 1; i++)
    {
        cin >> a[i];
        a[i]--;
    }
    Blocks b(n);
    vector<vector<int>> ans(n - 1, vector<int>(n));
    vector<vector<int>> G(n - 1, vector<int>(n));
    vector<int> F(n - 1);
    for(int i = 0; i < n - 1; i++)
    {
        int x = a[i];
        b.append(x);
        F[i] = b.getF();
        for(int j = 0; j < n; j++)
            G[i][j] = b.getG(j);
        for(int j = 0; j < n; j++)
        {
            if(a[i] == j) continue;
            int s = add(fact[n - 1], G[i][j]);
            if(i > 0)
            {
                s = sub(s, G[i - 1][j]);
                if(a[i - 1] == j)
                    s = add(s, F[i - 1]);
            }
            ans[i][j] = s;   
        }
    }
    
    long long res = 0;
    for(int i = 0; i < n - 1; i++)
        for(int j = 0; j < n; j++)
            res ^= ans[i][j] * 1ll * (i + 1) * 1ll * (j + 1);
    cout << res << endl;
}

int main() 
{
    precalc();
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int t;
    cin >> t;
    for(int i = 0; i < t; i++)
        solve();   
}