#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for(int i = 0; i< (int)(n); i++)
using ll = long long;
using ull = unsigned long long;
using vi = vector<int>;
ll INF = 2e18;
#define Yes cout << "Yes" << endl
#define No cout << "No" << endl
#define YN {cout<<"Yes"<<endl;}else{cout<<"No"<<endl;} // true → Yes false → No
// cout << fixed << setprecision(20);

int main() {
    ll N; cin>>N;
    ll ok = 0,ng = 1000000000;
    while(abs(ok-ng)>1) {
        ll mid = (ok+ng)/2;
        if(mid*mid > N) ng = mid;
        else ok = mid;
    }
    cout << ok << endl;
}