func_code_string: #include <bits/stdc++.h>   using namespace std;   const int N = 100000 + 6;   int g[N];   int main() {     int n, m, v, i;     cin >> n >> m >> v;     long long top = 1 + (n - 1) * (n - 2) / 2;     if (n - 1 > m || top < (long long)m) {       cout << -1;       return 0;     }     --v;     for (i = 0; i < n; ++i) g[i] = i;     swap(g[1], g[v]);     for (i = 0; i < n - 1; ++i) {       cout << g[i] + 1 <<     << g[i + 1] + 1 << endl;       --m;     }     int j;     for (i = 1; i < n - 1 && m; ++i) {       for (j = i + 2; j < n && m; ++j) {         cout << g[i] + 1 <<     << g[j] + 1 << endl;         --m;       }     }     return 0;   }   