#include<bits/stdc++.h>
using namespace std;

int main() {
    int t,count = 0;
    cin>>t;
    
    for(int i =1;i*i<=t;i++){
    	if(i*i<=t){
    		count++;
    	}
    	if(i*(i+1)<=t){
    		count++;
    	}
    }
    cout<<count<<endl;
    
}