func_code_string: #include <bits/stdc++.h>   using namespace std;   using ll = long long;   int n, m;   bool check(int mid) {     ll cnt = m * 1ll * mid, C = 1, ret = 1;     for (int i = 1; i <= min(m, mid) && cnt; i++) {       C = C * (mid - i + 1) / i;       if (cnt >= C * i)         cnt -= C * i, ret += C;       else {         ret += cnt / i;         break;       }       if (ret >= n) return 1;     }     return ret >= n;   }   int main() {     ios::sync_with_stdio(false);     int T;     cin >> T;     while (T--) {       cin >> n >> m;       int l = 0, r = n, ans = -1;       while (l <= r) {         int mid = (l + r) >> 1;         if (check(mid))           ans = mid, r = mid - 1;         else           l = mid + 1;       }       cout << ans << endl;     }     return 0;   }   