#include <iostream>
#include <vector>
#include <set>
using namespace std;


int main() {
    ios_base::sync_with_stdio(false);
    int n;
    cin >> n;

    vector<int> v(n);
    set<pair<int, int>> st;
    int sum = 0;
    for(int i = 0; i < n; i++) {
        cin >> v[i];
        sum += v[i];

        st.insert(make_pair(v[i], i));
    }
    if(sum - n >= n) {
        cout << "PROBLEM" << endl;
        return 0;
    }

    for(int i = 0; i < n; i++) {
        auto F = st.begin();
        auto E = st.end();
        E--;

        if(F->first > 0 and E->first > 0 and E->second != F->second) {
            cout << E->second + 1 << " " << F->second + 1 << endl;

            pair<int, int> tmp1 = *F, tmp2 = *E;
            st.erase(F);
            st.erase(E);

            tmp1.first--;
            tmp2.first--;

            if(tmp1.first > 0) {
                st.insert(tmp1);
            }
            if(tmp2.first > 0) {
                st.insert(tmp2);
            }
        }
    }
    return 0;
}