#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  map<long long, long long> m;
  long long k = 2, n;
  for (long long i = 1; i < 100001; i++) {
    m[i * i] = k;
    k += 2;
  }
  cin >> n;
  long long x = sqrt(n);
  long long l = x * x, r = (x + 1) * (x + 1);
  if (l - n == 0)
    cout << m[l];
  else if (n - l < r - n)
    cout << m[l] + 1;
  else
    cout << m[r];
  return 0;
}
