#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  if (n == 1) {
    cout << 2 << endl;
    return 0;
  } else if (n == 2) {
    cout << 3 << endl;
    return 0;
  } else {
    double tmp = sqrt(n);
    int a = floor(tmp);
    if (n == a * a) {
      cout << a + a << endl;
      return 0;
    }
    if (n <= a * (a + 1))
      cout << a + a + 1 << endl;
    else
      cout << a + a + 2 << endl;
  }
}
