#include<bits/stdc++.h>
using namespace std;
using ll=long long;
#define all(v) v.begin(),v.end()
#define rall(v) v.rbegin(),v.rend()
template<class T> bool chmax(T &a, T b){if (a < b){a = b;return true;} else return false;}
template<class T> bool chmin(T &a, T b){if (a > b){a = b;return true;} else return false;}

void Solve(){
    ll N;
    cin>>N;
    ll ok=0,ng=1e9+10;
    while(ng-ok>1){
        ll mid=(ok+ng)/2;
        if(mid*mid<=N)ok=mid;
        else ng=mid;
    }
    cout<<ok<<"\n";
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    Solve();
}