#include <bits/stdc++.h>
using namespace std;
const int inf = 2000000000;
const long long infLL = 9000000000000000000;
template <typename first, typename second>
ostream& operator<<(ostream& os, const pair<first, second>& p) {
  return os << "(" << p.first << ", " << p.second << ")";
}
template <typename T>
ostream& operator<<(ostream& os, const vector<T>& v) {
  os << "{";
  for (auto it = v.begin(); it != v.end(); ++it) {
    if (it != v.begin()) os << ", ";
    os << *it;
  }
  return os << "}";
}
template <typename T>
ostream& operator<<(ostream& os, const set<T>& v) {
  os << "[";
  for (auto it = v.begin(); it != v.end(); ++it) {
    if (it != v.begin()) os << ",";
    os << *it;
  }
  return os << "]";
}
template <typename T>
ostream& operator<<(ostream& os, const multiset<T>& v) {
  os << "[";
  for (auto it = v.begin(); it != v.end(); ++it) {
    if (it != v.begin()) os << ", ";
    os << *it;
  }
  return os << "]";
}
template <typename first, typename second>
ostream& operator<<(ostream& os, const map<first, second>& v) {
  os << "[";
  for (auto it = v.begin(); it != v.end(); ++it) {
    if (it != v.begin()) os << ", ";
    os << it->first << " = " << it->second;
  }
  return os << "]";
}
void faltu() { cerr << '\n'; }
template <typename T>
void faltu(T a[], int n) {
  for (int i = 0; i < n; ++i) cerr << a[i] << ' ';
  cerr << '\n';
}
template <typename T, typename... hello>
void faltu(T arg, const hello&... rest) {
  cerr << arg << ' ';
  faltu(rest...);
}
int n;
int a[505];
vector<pair<int, int> > vec;
vector<pair<int, int> > store;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  cin >> n;
  for (int i = 1; i <= n; ++i) {
    cin >> a[i];
    vec.push_back(make_pair(a[i], i));
  }
  int idx = -1;
  int ans = n - 1;
  sort(vec.begin(), vec.end(), greater<pair<int, int> >());
  for (int i = 1; i < (int)vec.size(); ++i) {
    int u = vec[i - 1].second, v = vec[i].second;
    if (a[u] && a[v]) {
      --a[u];
      --a[v];
      store.push_back(make_pair(u, v));
    } else {
      idx = i;
      break;
    }
  }
  if (idx != -1) {
    ans = idx - 1;
    bool ok = 0;
    for (int i = 0, j = idx; i < idx && j < (int)vec.size(); ++i, ++j) {
      int u = vec[i].second, v = vec[j].second;
      if (a[u] && a[v]) {
        --a[u];
        --a[v];
        store.push_back(make_pair(u, v));
        if (i == 0) ok = 1;
        --i;
      } else {
        --j;
      }
    }
    if (ok) ++ans;
  }
  if ((int)store.size() < n - 1) {
    cout << "NO" << '\n';
    return 0;
  }
  assert((int)store.size() == n - 1);
  cout << "YES"
       << " " << ans << '\n';
  cout << (int)store.size() << '\n';
  for (auto x : store) cout << x.first << " " << x.second << '\n';
}
