Here is my code. When compiling using g++ 12.1.0 on my local machine or using GNU G++ 20 on the judging machine, it always stop the input after the first loop of the first loop. Like it showns here. With the debug code below, it output something like 5 ? 1 1 > g 1- ? 2 1 2 > 2 ? 1 2 > u 1- ! gu??? where lines start with > is my input.

But when compiling with Clang++ on my local machine or on judge machine, it works well.

P.S. please ignore the WA on clang++, it is caused by making too many queries, which can be solved using binary search but I've not implement that yet.

Dbg Code: ```

include <bits/stdc++.h>

using namespace std;

define endl "\n"

pragma GCC optimize(3, "Ofast", "inline")

typedef vector vi; const int INF = 2e9;

define yesnosolve cout << (solve() ? "NO" : "YES") << endl

char q1(int pos) { char c; cout << "? 1 " << pos + 1 << endl << flush; scanf("%s", &c); return c; }

int q2(int pos1, int pos2) { int ans; cout << "? 2 " << pos1 + 1 << ' ' << pos2 + 1 << endl << flush; cin >> ans; return ans; }

void solve() { int len; cin >> len; vector res(len, '?');

res[0] = q1(0);
// cerr << res[0] << endl
//      << flush;
// cerr << len << '-' << endl;
for (int i = 1; i < len; i++)
{
    cerr << i << '-' << endl;
    set<char> st;
    bool f = false;
    for (int j = i - 1; j >= 0; j--)
    {
        st.insert(res[j]);
        if (q2(j, i) == int(st.size()))
        {
            res[i] = res[j];
            f = true;
            break;
        }
    }

    if (!f)
        res[i] = q1(i);

    cerr << i << '-' << endl;
}

cout << "! ";
for (auto &a : res)
    cout << a;
cout << endl
     << flush;

}

int main() { // cin.tie(nullptr); // cout.tie(nullptr); // ios_base::sync_with_stdio(0);

// int T;
// cin >> T;
// while (T--)
solve();

return 0;

} ```