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.

Sample test(s)

input

1

output

1

input

25

output

4

Note

Illustration to the second sample:

 

 

水题、

 

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
const int INF = 1e9;
const double eps = 1e-6;
int cas = 1;


int main()
{
    #ifdef LOCAL
//    freopen("case.txt","r",stdin);
    #endif
    int n,ans,sum,sum2;
    while(cin>>n)
    {
        ans = sum = sum2 = 0;
        while(true)
        {
            if(sum2 > n) break;
            ans ++ ;
            sum += ans;
            sum2 += sum;
        }
        cout << ans-1 << endl;
    }
    return 0;
}