#include<bits/stdc++.h>
using namespace std;
using LL=long long;
using ULL=unsigned long long;
#define rep(i,n) for(int i=0;i<(n);i++)

ULL sqrt_int(ULL x){
  ULL l=0, r=min(2000000000ull,x+1);
  while(r-l>1){
    ULL m=(l+r)/2;
    if(m*m<=x) l=m; else r=m;
  }
  return l;
}

int main(){
  ULL N; cin>>N;
  ULL Q = sqrt_int(N);
  ULL ans=Q*2;
  if(Q*Q==N) ans--;
  cout<<ans<<endl;
  return 0;
}