#include <bits/stdc++.h>
using namespace std;
int main() {
  int x;
  cin >> x;
  if (x == 3)
    puts("5");
  else {
    int ans = 1;
    while (ans * ans + 1 < 2 * x) ans += 2;
    cout << ans << endl;
  }
  return 0;
}
