codeforces——492A——Vanya and Cubes

A. Vanya and Cubes

time limit per test
1 second

memory limit per test
256 megabytes

input
standard input

output
standard output

Vanya got n cubes. He decided to build a pyramid from them. Vanya wants to build the pyramid as follows: the top level of the pyramid must consist of
1 cube, the second level must consist of
1 + 2 = 3 cubes, the third level must have 1 + 2 + 3 = 6 cubes, and so on. Thus, the
i-th level of the pyramid must have
1 + 2 + ... + (i - 1) + i cubes.

Vanya wants to know what is the maximum height of the pyramid that he can make using the given cubes.

Input
The first line contains integer n (1 ≤ n ≤ 104) — the number of cubes given to Vanya.

Output
Print the maximum possible height of the pyramid in the single line.

Examples

Input

1

Output

1

Input

25

Output

4

Note
Illustration to the second sample:



[align=left]水题
[/align]

#include<iostream>
#include<cstring>
#include<algorithm>
#include<map>
using namespace std;
int main()
{
int ans[40]= {0,1};
for(int i=2; i<=39; i++)
ans[i]=ans[i-1]+i*(i+1)/2;
int n;
while(cin>>n!=NULL)
for(int i=1;; i++)
if(n>=ans[i]&&n<ans[i+1])
{
cout<<i<<endl;
break;
}
return 0;
}