func_code_string: #include <bits/stdc++.h>   using namespace std;   bool m[1001][1001];   bool ff[1001][1001];   int n, num;   int ans;   int main() {     cin >> n >> num;     for (int i = 1; i <= n; i++)       for (int j = i + 1; j <= i + num; j++)         if (!m[i][(j - 1) % n + 1]) {           m[i][(j - 1) % n + 1] = true;           m[(j - 1) % n + 1][i] = true;           ff[i][(j - 1) % n + 1] = true;         } else {           cout << -1 << endl;           return 0;         }     if (n == 1) {       cout << -1 << endl;       return 0;     }     cout << num * n << endl;     for (int i = 1; i <= n; i++)       for (int j = 1; j <= n; j++)         if (ff[i][j]) printf( %d %d n , i, j);   }   