#include <stdio.h>
#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf32 1000000000
#define Inf64 1000000000000000001LL

int main(){
	long long n;
	cin>>n;
	long long ans = sqrt(n);
	while(ans*ans>n)ans--;
	while((ans+1)*(ans+1)<=n)ans++;
	cout<<ans<<endl;
	
	return 0;
}