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


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

  long long left = 0;
  long long right = n + 1;
  while (right - left > 1) {
    long long mid = (right + left) / 2;
    long long d = n / mid;
    if (mid >= d) {
      right = mid;
    } else {
      left = mid;
    }
  }
  long long ans = right - 1 + n / right;

  cout << ans << '\n';
  return 0;
}