func_code_string: #include <bits/stdc++.h>   using namespace std;   bool isp(const int x) {     if (x <= 1) return false;     for (int i = 2; i * i <= x; ++i)       if (x % i == 0) return false;     return true;   }   int pow(int x, int e, const int MOD) {     int r = 1;     for (; e; e >>= 1, x = (long long)x * x % MOD)       if (e & 1) r = (long long)r * x % MOD;     return r;   }   bool isr(int n, int p) {     for (int i = 2, q = p - 1; i * i <= q; ++i)       if (q % i == 0) {         if (pow(n, i, p) == 1 || pow(n, q / i, p) == 1) return false;       }     return true;   }   int main() {     int n, x;     scanf( %d%d , &n, &x);     if (!isp(n + 1)) return puts( -1 ), 0;     for (--x; x > 1; --x)       if (isr(x, n + 1)) return printf( %d n , x), 0;     return puts( -1 ), 0;   }   