#include <bits/stdc++.h>
#include <atcoder/fenwicktree>
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
using namespace std;
long long f(long long x, long long y) {
  if(x == 1 || y == 1) {
    return 1;
  } else if(__gcd(x, y) > 1 || x == 0 || y == 0) {
    return 0;
  } else {
    return (x - 1) * (y - 1);
  }
}
int main() {
  cin.tie(0); cout.tie(0);
  ios::sync_with_stdio(false);
  int N;
  cin >> N;
  vector<int> A(N);
  map<int, vector<int>> mp;
  for(int i = 0; i < N; i++) {
    cin >> A[i];
    int B = A[i];
    for(int j = 2; j * j <= A[i]; j++) {
      if(B % j == 0) {
        while(B % j == 0) B /= j;
        if(mp.count(j) == 0) {
          mp[j] = vector<int>{i};
        } else {
          mp[j].emplace_back(i);
        }
      }
    }
    if(B > 1) {
      if(mp.count(B) == 0) {
        mp[B] = vector<int>{i};
      } else {
        mp[B].emplace_back(i);
      }
    }
  }
  for(int i = 0; i < N; i++) {
    if(A[i] == 1) {
      cout << 1 << '\n';
      if(i == 0) {
        cout << 1 << ' ' << 2 << '\n';
      } else {
        cout << 1 << ' ' << i + 1 << '\n';
      }
      for(int i = 1; i < N - 1; i++) {
        cout << 1 << ' ' << N - i << '\n';
      }
      return 0;
    }
  }
  for(auto [p, v] : mp) {
    if((int) v.size() > 1) {
      cout << 0 << '\n';
      cout << v[0] + 1 << ' ' << v[1] + 1 << '\n';
      for(int i = 1; i < N - 1; i++) {
        cout << 1 << ' ' << N - i << '\n';
      }
      return 0;
    }
  }
  priority_queue<pair<long long, int>, vector<pair<long long, int>>, greater<pair<long long, int>>> pq;
  atcoder::fenwick_tree<int> fw(N + N);
  for(int i = 0; i < N; i++) {
    pq.push(make_pair(A[i], i));
  }
  vector<pair<int, int>> ans;
  for(int t = 0; t < N - 1; t++) {
    pair<long long, int> p = pq.top();
    pq.pop();
    pair<long long, int> q = pq.top();
    pq.pop();
    long long x = p.first;
    long long y = q.first;
    int ix = p.second;
    int iy = q.second;
    long long z = f(x, y);
    ans.push_back(make_pair(ix - fw.sum(0, ix), iy - fw.sum(0, iy)));
    fw.add(ix, 1);
    fw.add(iy, 1);
    pq.push(make_pair(z, N + t));
  }
  cout << pq.top().first << '\n';
  for(pair<int, int> a : ans) {
    cout << a.first + 1 << ' ' << a.second + 1 << '\n';
  }
  return 0;
}