#include<fstream.h>
long n,m[10000];

int prim(int x,int y)
{while(x!=y)if(x>y)x=x-y;
		else y=y-x;
return x;
}
int main()
{ifstream f("pairs.in");
int i,j,nr;
f>>n;for(i=1;i<n+1;i=i+1)f>>m[i];
f.close();
ofstream g("pairs.out");
for(i=1;i<n;i=i+1)
 for(j=i;j<n+1;j=j+1)
if(prim(m[i],m[j])==1) nr++;
g<<nr;
g.close();
return 0;}