#include <bits/stdc++.h>
using namespace std;
#define int long long
signed main(){
    int ac = 1, wa = 1e9+7;
    int n;
    cin>>n;
    while(wa-ac>1){
    	int md = (wa+ac)/2;
    	if(md*md <= n) ac = md;
    	else wa = md;
    }
    cout<<ac<<endl;
}