#include <bits/stdc++.h>
using namespace std;
const int MAXN = 100005;
long long po[MAXN];
int main(void) {
  long long n;
  scanf("%I64d", &n);
  for (int i = 0; i <= 100000; i++) po[i] = 1LL * i * i;
  long long posa = lower_bound(po, po + 100000, n) - po;
  long long posb = upper_bound(po, po + 100000, n) - po;
  if (posa < posb)
    printf("%I64d\n", 2 * posa);
  else {
    if (n <= (posa - 1) * (posa - 1) + (posa - 1))
      printf("%I64d\n", 2 * (posa - 1) + 1);
    else
      printf("%I64d\n", 2 * posa);
  }
  return 0;
}
