#include <bits/stdc++.h>
 
using namespace std;
 
int main() {
    int t;
    cin >> t;
    while(t--){
        int n;
        cin >> n;
        string a, b;
        getchar();
        getline(cin, a);
        getline(cin, b);
        int ans = 0;
        for(int i = 0; i < n; i++)
            if (a[i] != b[i])
                ans++;
        cout << ans << '\n';
    }
}

#include <bits/stdc++.h>
#define int int64_t
 
using namespace std;
 
int32_t main() {
    int a, b, c, d, e;
    cin >> a >> b >> c >> d >> e;
    b -= d;
    c -= e;
    int D = b * b - 4 * a * c;
    cout.precision(6);
    if (D < 0)
        cout << 0;
    else if (D == 0){
        cout << 1 << '\n';
        int x = ((double)(-b) + sqrt(D)) / 2.0 / a;
        cout << fixed << x << ' ' << d * x + e << '\n';
    }
    else{
        cout << 2 << '\n';
        double x1 = (-b + sqrt(D)) / 2.0 / a;
        cout << fixed << x1 << ' ' << d * x1 + e << '\n';
        double x2 = (-b - sqrt(D)) / 2.0 / a;
        cout << fixed << x2 << ' ' << d * x2 + e << '\n';
    }
}