func_code_string: #include <bits/stdc++.h>   using namespace std;   int n, k, a[10010];   bool vs[3000][3000];   int main() {     cin >> n >> k;     for (int i = n + 1; i <= n + k; i++) {       a[i] = i - n;     }     for (int i = 1; i <= n; i++) a[i] = i;     for (int i = 1; i <= n; i++) {       for (int j = i + 1; j <= i + k; j++) {         if (!vs[a[i]][a[j]] && !vs[a[j]][a[i]]) {           vs[a[i]][a[j]] = true;           vs[a[j]][a[i]] = true;         } else {           cout << -1;           exit(0);         }       }     }     if (n == 1) {       cout << -1;       exit(0);     }     cout << n * k <<   n ;     for (int i = 1; i <= n; i++)       for (int j = i + 1; j <= i + k; j++) cout << a[i] <<     << a[j] <<   n ;   }   