#pragma GCC optimize("O3,unroll-loops")
#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define Waimai ios::sync_with_stdio(false), cin.tie(0)
#define FOR(x,a,b) for(int x = a, I = b; x <= I; x++)
#define pb emplace_back
#define F first
#define S second

const int SIZE = 55;

int n;
int a[SIZE];
priority_queue<pair<int, int>> pq;

void solve() {
    cin >> n;
    int s = 0;
    FOR (i, 1, n) {
        cin >> a[i];
        s += a[i];
    }
    if (s & 1) {
        cout << "no\n";
        return;
    }
    if (*max_element(a + 1, a + n + 1) > s / 2) {
        cout << "no\n";
        return;
    }
    FOR (i, 1, n) if (a[i]) pq.emplace(a[i], i);
    cout << "yes\n";
    while (pq.size()) {
        auto [cx, x] = pq.top(); pq.pop();
        auto [cy, y] = pq.top(); pq.pop();
        cout << x << ' ' << y << '\n';
        cx--, cy--;
        if (cx) pq.emplace(cx, x);
        if (cy) pq.emplace(cy, y);
    }
}

int main() {
    Waimai;
    solve();
}