#include <stdio.h>
#include<string.h>
#define M 1000000
int f[M+1];
int main()
{
int i,j,co,n;
memset(f,0,sizeof(f));
co=1;
for(i=2;i<=M;i++)
{
if(f[i]==0)
{
for(j=i;j<=M;j+=i)
f[j]=co;
co++;
}
}
while(scanf("%d",&n)!=EOF)
{
printf("%d\n",f[n]);
}
return 0;
}