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: 

<image>
#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e4;
int sum[maxn];
void preprocess() {
  sum[0] = 0;
  int mx = 0;
  for (int i = 1; i < maxn; i++) {
    sum[i] = sum[i - 1] + i;
    mx = i;
    if (sum[i] > maxn) break;
  }
  for (int i = 1; i <= mx; i++) {
    sum[i] += sum[i - 1];
  }
}
int main() {
  preprocess();
  int n;
  while (cin >> n) {
    int h = 0;
    while (sum[h] <= n) h++;
    cout << h - 1 << endl;
  }
}
