2015 HUAS Provincial Select Contest #2~C

Description

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.

Sample Input

Input

1

Output

1

Input

25

Output

4

解题思路：这个问题就是判断输入的数的和是在金字塔的第几行，但是要注意的是，如果输入的数不是在这一行的最后一位，那么输出的数字需要减去1，如果是最后一位则不需要减去1；在第二次输入数字时，注意和的清零，还有计算次数的数应赋值为1，否则将出现错误。若输入的数字为0，则应该推出程序。

程序代码：

#include<cstdio> int main() { int n,count,sum; while(scanf("%d",&n)==1&&n) { 
 count=1; sum=0; for(int i=1;i<=count;i++)  { sum=sum+((1+i)*i)/2; if(sum>=n)  { if(sum==n) {
 printf("%d\n",count);
 break;
 } else 
 { 
 printf("%d\n",count-1);
 break;
 } } 
 count++; } }  return 0; }