#include <bits/stdc++.h>
using namespace std;

typedef long long ll;

int main() {
    ll n;
    cin >> n;

    int cnt = 0;
    //  only need to iterate while k*k <= n
    for (long long k = 1; k * k <= n; ++k) {
        ll sq = k * k;
        ll conq = k * (k + 1);

        if (sq <= n) cnt++;
        if (conq <= n) cnt++;
    }

    cout << cnt << endl;
    return 0;
}