#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, s, e) for (int i = (int)(s); i < (int)(e); ++i)
#define all(a) (a).begin(),(a).end()

int main() {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    
    ll N;
    cin >> N;
    
    ll ok = 1, ng = 1e9 + 10;
    while (ng - ok > 1) {
        ll mid = (ng - ok) / 2 + ok;
        
        if (mid*mid <= N) ok = mid;
        else ng = mid;
    }
    cout << ok << '\n';
}