int main(){
int a[6]={2,3,5,7,11,13},b[6]={4,6,8,9,10,12},s,i,j,n=0;
scanf("%d",&s);
for(i=0;i<6;i++)for(j=0;j<6;j++)s-a[i]*b[j]||n++;
printf("%.12lf",n*1./36);
return 0;
}