include <bits/stdc++.h>

define ll long long

define ld long double

using namespace std; int main(){

ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
ll n;
cin>>n;
ll ans = 1;
for(int i = 2; i<=sqrt(n); ++i){
    if(i*i <= n){
        ans++;
    }
}
cout<<ans;

}//TECHNOBLADE NEVER DIE