func_code_string: #include <bits/stdc++.h>   using namespace std;   pair<int, int> a[200];   int n, x;   vector<pair<int, int> > res;   int main() {     int sum = 0;     cin >> n;     cin >> a[0].first;     a[0].second = 0;     sum += a[0].first;     for (int i = 1; i < n; i++) {       cin >> a[i].first;       a[i].second = i;       sum += a[i].first;     }     if (a[0].first == 0 || sum < n - 1) {       cout << -1;       return 0;     }     sort(a + 1, a + n);     reverse(a + 1, a + n);     int x = 0;     int y = 1;     cout << n - 1 << endl;     while (y < n) {       cout << a[x].second + 1 <<     << a[y].second + 1 << endl;       y++;       a[x].first--;       if (a[x].first == 0) x++;     }     return 0;   }   