#include<fstream.h>
#define dim 100001
int v[dim];
int jum;
int prim(int x,int y)
{if(((x%2)==0)&&((y%2)==0)) return 0;
 if(((x%y)==0)||((y%x)==0)) return 0;
 if(((x-y)==1)||((y-x)==1)) return 1;
 do
  {jum=x%y;
   x=y;
   y=jum;
  }
 while(jum);
 if(x==1) return 1;
return 0;
}
int main()
{ifstream f("pairs.in");
 ofstream g("pairs.out");
 unsigned long n,i,j,k,cont;
 cont=0;
 f>>n;
 f>>v[1];
 for(i=2;i<=n;i++)
  {f>>v[i];
   for(j=1;j<i;j++)
   cont+=prim(v[i],v[j]);
  }
f.close();
 g<<cont<<'\n';
g.close();
return 0;
}