#include <cstdio>
FILE *in, *out;
int v[100000],n,contor;

bool prime (int a, int b)
{
  
  if (b==1) return true;
  int c=a%b;
  while (c)
  {
    a=b;
    b=c;
    c=a%b;
  }
  
  if (b==1)  return true;
 
  return false;
}


int main()
{
  in = fopen ("pairs.in", "r");
  out = fopen ("pairs.out", "w");
  fscanf (in, "%d", &n);
  int i,j;
  for (i=1; i<=n; ++i)
    fscanf (in, "%d", &v[i]);
 
   
  for (i=1; i<n; i++)
    for (j=i+1; j<=n; j++)
      if (prime (v[i],v[j]))
        contor++,printf ("%d %d\n",v[i],v[j]);
   
    
  fprintf (out, "%d", contor);
  
  fclose (in);
  fclose (out);
  return 0;
}