#include <bits/stdc++.h>
using namespace std;
void err(istream_iterator<string> it) {}
template <typename T, typename... Args>
void err(istream_iterator<string> it, T a, Args... args) {
  cerr << *it << " = " << a << '\n';
  err(++it, args...);
}
signed main(void) {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long n;
  cin >> n;
  if (n == 2) {
    cout << 3 << '\n';
    return 0;
  }
  long long x = (long long)sqrt(n) * (long long)sqrt(n);
  long long y = sqrt(n);
  if (x == n) {
    cout << 2 * y << '\n';
  } else if (n - x <= y) {
    cout << 2 * y + 1 << '\n';
  } else {
    cout << 2 * y + 2 << '\n';
  }
}
