Vanya and Cubes

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.

Sample test(s)

input

1

output

1

input

25

output

4

Note

Illustration to the second sample:

题意：简单明了，就是a[1]=1;a[i]=a[i+1]+i;给出一个数，看它最多放在第几层。

#include
using namespace std;
int a[10010];
int main()
{
    a[1]=1;
    long long int sum,m;
    for(int i=2;i<=10000;i++)
    a[i]=a[i-1]+i;
    while(cin>>m)
    {
            for(int i=1;i<=10000;i++)
            {

                m-=a[i];
               if(m


可以预处理一下，

#include 
#include 
using namespace std;

int a[10005];

int main(){
//  freopen("in.txt", "r", stdin);
    int foo = 0;
    int sum = 0;
    for(int i=1; ; i++){
        int t = foo;
        if(sum > 10000) break;
        foo += i;
        for(int j=0; j

效率会快一些。。。