#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main() {
    int n;
    cin >> n;
    vector<pair<int,int>> stacks(n);
    for (int i = 0; i < n; i++) {
        cin >> stacks[i].first;
        stacks[i].second = i+1;
    }
    vector<pair<int,int>> moves;
    while (true) {
        sort(stacks.rbegin(),stacks.rend());
        if (stacks[1].first == 0) break;
        moves.push_back({stacks[0].second,stacks[1].second});
        stacks[0].first--;
        stacks[1].first--;
    }
    if (stacks[0].first == 0) {
        cout << "yes\n";
        for (auto move : moves) {
            cout << move.first << " " << move.second << "\n";
        }
    } else {
        cout << "no\n";
    }
}