func_code_string: #include <bits/stdc++.h>   using namespace std;   bool test(long long, long long, long long);   int main(void) {     long long n, m;     cin >> n >> m;     long long first, last;     first = 0;     last = sqrt(2 * n) + 1;     if (m >= n) {       cout << n;       return 0;     }     while (test(first, n, m) == 0) {       long long med;       med = (first + last) / 2;       if (test(med, n, m) == 1)         last = med;       else         first = med;       if (last - first == 1 && test(first, n, m) == 0) first = last;     }     cout << first + m;     return 0;   }   bool test(long long day, long long n, long long m) {     if (day % 2 == 0) {       if ((day / 2) * (day + 1) >= (n - m)) return 1;     } else {       if (day * ((day + 1) / 2) >= (n - m)) return 1;     }     return 0;   }   