#include<stdio.h>
#include<math.h>
FILE *f1,*f2;
long a,b,i,j,n,v[300000];
int main(){
	f1=fopen("ciur.in","r");
	f2=fopen("ciur.out","w");
	fscanf(f1,"%ld",&n);
	a=13;
	j=6;
	v[1]=2;
	v[2]=3;
	v[3]=5;
	v[4]=7;
	v[5]=11;
	v[6]=13;
	while(a<n){
		a++;
		while(a%2==0||a%3==0||a%5==0||a%7==0||a%11==0||a%13==0){
			a++;
		}
		j++;
		v[j]=a;
	}
	a=0;
	b=j;
	while(v[b]>n){
		b--;
	}
	a=floor(sqrt(n))+1;
	if(a<n){
		n=a;
	}
	a=0;
	for(i=1;i<=b;i++){
		if(v[i]>0){
			a++;
			if(v[i]<=n){
				for(j=i+1;j<=b;j++){
					if(v[j]%v[i]==0){
						v[j]=-1;
					}
				}
			}
		}			
	}
	fprintf(f2,"%ld",a);
	return 0;
}