#include <bits/stdc++.h>
using namespace std;
int gcd(int a, int b) {
  if (a == 1 || b == 1) return 1;
  int v1 = min(a, b);
  b = max(a, b);
  a = v1;
  while (b) {
    a %= b;
    swap(a, b);
  }
  return a;
}
int Search(int a, int b) {
  for (int i = 2;; ++i) {
    if (i == a || i == b) continue;
    if (gcd(i, a) == 1 && gcd(i, b) == 1) return i;
  }
  return -1;
}
int main() {
  int n;
  vector<int> a, out;
  auto f = stdin;
  fscanf(f, "%d", &n);
  for (int i = 0; i < n; ++i) {
    int v;
    fscanf(f, "%d", &v);
    a.push_back(v);
  }
  int k = 0;
  for (int i = 0; i < n - 1; ++i) {
    out.push_back(a[i]);
    int v1 = a[i];
    int v2 = a[i + 1];
    if (gcd(v1, v2) != 1) {
      ++k;
      out.push_back(Search(v1, v2));
    }
  }
  out.push_back(a[n - 1]);
  printf("%d\n", k);
  for (int i = 0; i < out.size(); ++i) printf("%d ", out[i]);
  return 0;
}
