#include <iostream>
#include <vector>
#include <algorithm>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using mint = modint998244353;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using vvvll = vector<vvll>;
using vmi = vector<mint>;
using vvmi = vector<vmi>;
using vvvmi = vector<vvmi>;
#define all(a) (a).begin(), (a).end()
#define rep2(i, m, n) for (int i = (m); i < (n); ++i)
#define rep(i, n) rep2(i, 0, n)
#define drep2(i, m, n) for (int i = (m)-1; i >= (n); --i)
#define drep(i, n) drep2(i, n, 0)

int main(){
    ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    ll n; cin >> n;
    ll left = 1, right = 2e9;
    ll mid;
    while(right- left > 1){
        mid = (right + left)/2;
        if(mid*mid <= n){
            left = mid;
        }else{
            right = mid;
        }
    }
    cout << left << endl;

    return 0;
}