func_code_string: #include <bits/stdc++.h>   using namespace std;   int ar[111];   int in[111];   long long n, s, now, t;   int main() {     cin >> n;     for (int i = 0; i < n; i++) {       cin >> ar[i];       s += ar[i];       in[i] = i;     }     if (s < n - 1 || ar[0] == 0) {       cout << -1;       return 0;     }     for (int ii = 1; ii < n - 1; ii++)       for (int i = 1; i < n - 1; i++)         if (ar[in[i]] < ar[in[i + 1]]) swap(in[i], in[i + 1]);     cout << n - 1;     s = 0;     now = 1;     while (now < n) {       while (ar[in[s]] > 0 && now < n) {         cout << endl << in[s] + 1 <<     << in[now++] + 1;         ar[in[s]]--;       }       s++;     }     return 0;   }   