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

    }
    cout<<counter/2+1<<endl;
}