func_code_string: #include <bits/stdc++.h>   using namespace std;   inline int read() {     int x = 0, f = 1;     char ch = getchar();     while (ch <  0  || ch >  9 ) {       if (ch ==  - ) f = -1;       ch = getchar();     }     while (ch >=  0  && ch <=  9 ) {       x = x * 10 + ch -  0 ;       ch = getchar();     }     return x * f;   }   int n, m, v;   int main() {     n = read();     m = read();     v = read();     if (m > (long long)(n - 1) * (n - 2) / 2 + 1 || m < n - 1) {       printf( -1 n );     } else {       for (int i = 1; i <= n; i++) {         if (i != v) {           printf( %d %d n , v, i);         }       }       int s = (v == 1 ? 2 : 1);       m -= (n - 1);       for (int i = 1; i <= n; i++) {         if (i != s && i != v) {           for (int j = i + 1; j <= n; j++) {             if (j != s && j != v) {               if (!m--) {                 return 0;               }               printf( %d %d n , i, j);             }           }         }       }     }     return 0;   }   