#include <iostream>
using namespace std;
int solve(int n){
    int ans=0,sum;
    for(int i=1;i<n+1;i++){
        sum=0;
        for(int j=1;j<i+1;j++){
            if(i%j==0)sum++;
        }
        if(sum==2)ans++;
    }
    return ans;
}
int main(void){
    int n;
    while(cin>>n){
        cout<<solve(n)<<endl;
    }
    return 0;
}