#include "bits/stdc++.h" 
using namespace std; 
typedef long long ll;

int main() {
    ll n;cin >> n;
    ll l = -1, r = 1000000000;
    while(r - l > 1) {
        ll mid = l + (r - l) / 2;
        if (n <= mid * (mid + 1)) {
            r = mid;
        }
        else {
            l = mid;
        }
    }
    cout << n / r + r - 1 << endl;
    return 0;
}