#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  int t = 1;
  while (t--) {
    long long n;
    cin >> n;
    const long long N = 100000;
    long long ans[N] = {0};
    int add = 1;
    for (int i = 2; i + 1 < N - 1; i += 2) {
      ans[i] = ans[i - 1] + add;
      if (n > ans[i - 1] && n <= ans[i]) {
        cout << i << "\n";
        break;
      }
      ans[i + 1] = ans[i] + add;
      if (n > ans[i] && n <= ans[i + 1]) {
        cout << i + 1 << "\n";
        break;
      }
      add++;
    }
  }
  return 0;
}
