#include <bits/stdc++.h>
#define all(x) (x).begin(), (x).end()
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pi;
int main() {
    ios::sync_with_stdio(0); cin.tie(0);
    int n; cin >> n; priority_queue<pi> pq;
    vector<pi> dap;
    for (int i = 1; i <= n; i++) {
        int x; cin >> x;
        if (x == 0) continue;
        pq.push({x, i});
    }
    while (pq.size() >= 2) {
        pi a = pq.top(); pq.pop();
        pi b = pq.top(); pq.pop();
        a.first--; b.first--;
        dap.push_back({a.second, b.second});
        if (a.first) pq.push(a);
        if (b.first) pq.push(b);
    }
    if (pq.empty()) {
        cout << "yes\n";
        for (auto &x: dap) cout << x.first << ' ' << x.second << '\n';
    } else cout << "no\n";
    return 0;
}