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

void solve() {
    ll n;
    cin >> n;
    ll a = sqrt(n);
    ll b = sqrt(4 * n + 1);
    ll res = a + (b - 1) / 2;
    cout << res << "\n";
}

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    solve();
    return 0;
}