#include <fstream.h>
 long n,v[100000];
long prim(int a,int b)
{ while (a!=b) if(a>b) a=a-b;
	       else b=b-a;
	    return a;}

int main()
{ ifstream f("pairs.in");
  ofstream g("pairs.out");
  long  nr=0,i,j;
f>>n;
for (i=1;i<=n;i++) f>>v[i];
f.close();

for (i=1;i<=n-1;i++)
for (j=i+1;j<=n;j++) if(prim (v[i],v[j])==1)nr++;
g<<nr;
g.close();return 0;}