#include<stdio.h>
int main(){
			int a,b,c,n;

	while(scanf("%d",&n) != EOF){
		c=0;
			for(a=2;a<=n;a++){
				for(b=2;b<=n;b++){
					if(a%b==0&&a!=b){
						break;
					}else if(a%b==0&&a==b){
						c++;
					}else{
					}
				}
			}
			printf("%d\n",c);
	}
	return 0;
}