#include <bits/stdc++.h>

using namespace std;

#ifndef ONLINE_JUDGE
#include "trace.cpp"
#else
#define dbg(...)
#endif

int32_t main() {
  cin.tie(0) -> sync_with_stdio(0);
  int n;
  cin >> n;
  int ans = 0;
  for (int i = 1; i * i <= n; i++) {
    if (i * i <= n) ans += 1;
    if (i * (i + 1) <= n) ans += 1;
  }
  cout << ans;
  return 0;
}