#include <bits/stdc++.h>

using namespace std;

const int kMaxN = 1e5 + 10;

int a[kMaxN], n;
vector<pair<int, int>> ans;

int main() {
  ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
  }
  int k = max((accumulate(a, a + n, 0) + 1) / 2, *max_element(a, a + n));
  for (int m = k, t = k; t--;) {
    int flag = 0;
    pair<int, int> num;
    for (int i = 1; i <= n; i++) {
      if (a[i - 1] > 0) {
        for (int j = i + 1; j <= n; j++) {
          if (a[j - 1] > 0) {
            a[i - 1]--, a[j - 1]--;
            int w = *max_element(a, a + n);
            a[i - 1]++, a[j - 1]++;
            if (w <= (m - 1)) {
              num = {i, j}, flag = 1;
              break;
            }
          }
        }
        if (flag) break;
      }
    }
    if (!flag) {
      for (int i = 1; i <= n; i++) {
        if (a[i - 1] > 0) {
          a[i - 1]--;
          int w = *max_element(a, a + n);
          a[i - 1]++;
          if (w <= (m - 1)) {
            num = {i, i}, flag = 1;
            break;
          }
        }
      }
    }
    if (flag) {
      ans.push_back(num), a[num.first - 1]--;
      if (num.first != num.second) {
        a[num.second - 1]--;
      }
      m--;
    } else {
      int val = *max_element(a, a + n), p = 1;
      for (int i = 0; i < n; ++i) {
        if (a[i] == val) {
          p = i + 1;
          break;
        }
      }
      ans.emplace_back(p, p), a[p - 1]--, m--;
    }
  }
  cout << k << '\n';
  sort(ans.begin(), ans.end());
  for (int i = 0, j = 0; i < ans.size(); i++) {
    if (ans[i].first == ans[i].second && j < i) {
      ans[i].first = ans[j].second, ans[j].second = ans[j].first, (ans[i].first > ans[i].second) && (swap(ans[i].first, ans[i].second), 0), j++;
    }
  }
  sort(ans.begin(), ans.end());
  for (pair<int, int> i : ans) {
    cout << i.first << ' ' << i.second << '\n';
  }
  return 0;
}