#include<fstream.h>
int prim (int a,int b)
	{int d,ok=1;
		for (d=2;d<=a&&ok==1;d++)
			if (a%d==0&&b%d==0)
				ok=0;
	if (ok==0)
		return 0;
	else return 1;
}

int main (){
	ifstream in ("pairs.in") ;
	ofstream out ("pairs.out");
	int i,n,j,v[32000],nr=0,a;
	in>>n;
	for (i=0;i<n;i++)
		in>>v[i];
	for (i=0;i<n;i++)
		for (j=0;j<n;j++)
			if (prim (v[i],v[j])==1)
				nr++;
	out<<nr/2;
	return 0;
	}