#include<iostream>
using namespace std;

int main(){
	const int max_num=10000000;
	int prime[max_num];
	int prime2[max_num];
	int min_prime[168]={2 ,3 ,5 ,7 ,11 ,13 ,17 ,19 ,23 ,29 ,31 ,37 ,41 ,43 ,47 ,53 ,59 ,61 ,67 ,71 ,73 ,79 ,83 ,89 ,97 ,101 ,103 ,107 ,109 ,113 ,127 ,131 ,137 ,139 ,149 ,151 ,157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233 ,239 ,241 ,251 ,257 ,263 ,269 ,271 ,277 ,281 ,283 ,293 ,307 ,311 ,313 ,317 ,331 ,337 ,347 ,349 ,353 ,359 ,367 ,373 ,379 ,383 ,389 ,397 ,401 ,409 ,419 ,421 ,431 ,433 ,439 ,443 ,449 ,457 ,461 ,463 ,467 ,479 ,487 ,491 ,499 ,503 ,509 ,521 ,523 ,541 ,547 ,557 ,563 ,569 ,571 ,577 ,587 ,593 ,599 ,601 ,607 ,613 ,617 ,619 ,631 ,641 ,643 ,647 ,653 ,659 ,661 ,673 ,677 ,683 ,691 ,701 ,709 ,719 ,727 ,733 ,739 ,743 ,751 ,757 ,761 ,769 ,773 ,787 ,797 ,809 ,811 ,821 ,823 ,827 ,829 ,839 ,853 ,857 ,859 ,863 ,877 ,881 ,883 ,887 ,907 ,911 ,919 ,929 ,937 ,941 ,947 ,953 ,967 ,971 ,977 ,983 ,991 ,997 };
	int sosuu=0;
	int k=168;

	for(int i=0;i<168;i++){
		prime[i]=min_prime[i];
	}
	for(int i=1001;i<max_num;i+=2){
		sosuu=0;
		for(int j=0;j<168;j++){
			if(i%min_prime[j]==0){
				sosuu++;
			}
		}
		if(sosuu==0){
			prime[k]=i;
			k++;
		}
	}
	int l=0;
	for(int i=0;i<max_num;i++){
		if(i>=prime[l]){
			l++;
		}
		prime2[i]=l;
	}

	int n;

	while(cin>>n){
		cout<<prime2[n]<<endl;
	}

	return 0;
}