# include<iostream> # include<cmath> using namespace std; int prime(int x){ int sum=0; for(int i=2;i<=x;i++){ for(int j=2;j<=sqrt(i);j++){ if(i%j==0){ sum++; break; } } } sum=x-1-sum; return sum; } int main(){ int n; cin>>n; cout<<prime(n); return 0; }