#include<stdio.h>
int main(void)
{
	int n,i,limit;
	int prime[5000001];
	int count=0;
	for(n=2;n<=100000000;n++){
	limit = (int)sqrt(n);
		for(i=limit;i>=2;i--){
			if(n%i==0)
		break;
	}
	if(i==1)
		prime[count++]=n;
	}
	printf("%d",count);
    return 0;
}
