func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int ans, n, m, x, y;     cin >> n >> m;     int lo = (n + 1) / 2;     ans = (lo + m - 1) / m;     ans *= m;     if (ans > n)       cout << -1 << endl;     else       cout << ans << endl;     return 0;   }   