#include<bits/stdc++.h>
using namespace std;
int main()
{
    int n;
    cin>>n;
    int counter = 0;
    for(int i = 1;i*i<n;i++)
    {
        int balance =i*i;
        if(balance<n)
            counter++;
        if(i*(i+1)<=n)
        {
          counter++;
        }
    }
    cout<<counter<<endl;
}