#include <bits/stdc++.h>
using namespace std;
int main(){
	int s=0,h=1,g=1,i;
	for(i=1;s<=5000;i++){
        s+=g;
        h+=i;
        g=h;
	}
	cout<<s;
}
/**************************************************************
	Problem: 1146
	User: wangyiyang
	Language: C++
	Result: Accepted
	Time:3 ms
	Memory:2072 kb
****************************************************************/