#include<iostream>
#include<vector>
using namespace std;
int main()
{
    vector<unsigned long int> array;
    array.push_back(0);
    array.push_back(0);
    unsigned long int iter=2,n=2,number,end=3,count;
    cin>>number;
    array.push_back(3);
    if(number<=2)
        cout<<number;
	else if(number==3)
		cout<<"2";
    else
    {
        while(number>end)
        {
			n++;
            if(array[iter]==n)
            {
                count=iter;
                iter++;
            }
            else if(array[iter]>n)
                        count=iter;
            end+=count;
            array.push_back(end);
        }
      cout<<n;
    }    
}