func_code_string: #include <bits/stdc++.h>   using namespace std;   const long double epsilon = 1e-9;   int main() {     long long n, m, v;     cin >> n >> m >> v;     long long p = ((n - 1) * (n - 2)) / 2LL + 1;     if (m > p || m < n - 1) {       cout << -1 << endl;       return 0;     }     int other = 1;     if (v == 1) other = 2;     for (int i = 1; i <= n; i++) {       if (i == v)         continue;       else         cout << v <<     << i << endl;     }     m -= n - 1;     for (int i = 1; i <= n && m > 0; i++) {       if (i == v || i == other) continue;       for (int j = i + 1; j <= n && m > 0; j++) {         if (j == v || j == other || j == i) continue;         printf( %d %d n , i, j);         m--;       }     }     return 0;   }   