#include <bits/stdc++.h>
const double pi = acos(-1.0);
const long long mod = 1e9 + 7;
using namespace std;
int a[10005];
int sum[10005];
int main() {
  int N;
  scanf("%d", &N);
  a[1] = 1;
  sum[1] = 1;
  for (int i = 1; i <= 10000; i++) a[i + 1] = a[i] + i + 1;
  for (int i = 1; i <= 10000; i++) sum[i + 1] = sum[i] + a[i + 1];
  for (int i = 1; i <= 10000; i++) {
    if (N >= sum[i] && N < sum[i + 1]) {
      printf("%d\n", i);
      break;
    }
  }
  return 0;
}
