#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int n, i, j, k;
  cin >> n;
  if (n == 1 || n == 2) {
    cout << n + 1;
    return 0;
  }
  long long int l = 2;
  long long int sum = 4;
  for (i = 2; i <= n;) {
    long long int h = i + l;
    long long int mh = h + l;
    if (n > i && n <= h) {
      cout << sum;
      return 0;
    } else {
      sum++;
    }
    if (n > h && n <= (mh)) {
      cout << sum;
      return 0;
    } else {
      sum++;
    }
    l++;
    i = mh;
  }
}
