#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
  #include "settings/debug.cpp"
#else
  #define Debug(...) void(0)
#endif
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

int main() {
  ll n;
  cin >> n;
  ll sq = sqrtl(n);
  if (sq * sq > n) --sq;
  ll ans = sq * 2;
  if (n / sq == sq) --ans;
  cout << ans << endl;
  return 0;
}