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>

import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.StringTokenizer;

public class VanyaAndCubes {
	public static void main(String[] args) {
		out = new PrintWriter(new BufferedOutputStream(System.out));
		Reader in = new Reader();
		int n = in.readInt() - 1, i = 2, sum = 0, cubes = 1;
		for(; i < n; i++){
			sum = sum(i);
			if(n < sum) break;
			else {n -= sum; cubes++;}
		}
		out.println(cubes);
		in.close();
		out.close();
	}
	static int sum(int i){
		int sum = 0;
		for(; i > 0; i--) sum += i;
		return sum;
	}
	static PrintWriter out;
	static class Reader {
		BufferedReader br;
		StringTokenizer st;
		public Reader() {
			br = new BufferedReader(new InputStreamReader(System.in));
		}
		String read() {
			while (st == null || !st.hasMoreElements()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			return st.nextToken();
		}
		int readInt() {
			return Integer.parseInt(read());
		}
		long readLong() {
			return Long.parseLong(read());
		}
		double readDouble() {
			return Double.parseDouble(read());
		}
		char readChar() {
			return read().charAt(0);
		}
		int[] readIntArray(int n) {
			int[] a = new int[n];
			for (int i = 0; i < n; i++)
				a[i] = readInt();
			return a;
		}
		long[] readLongArray(int n) {
			long[] a = new long[n];
			for (int i = 0; i < n; i++)
				a[i] = readLong();
			return a;
		}
		double[] readDoubleArray(int n) {
			double[] a = new double[n];
			for (int i = 0; i < n; i++)
				a[i] = readDouble();
			return a;
		}
		String[] readStringArray(int n) {
			String[] s = new String[n];
			for (int i = 0; i < n; i++)
				s[i] = read();
			return s;
		}
		char[] readCharArray(int n) {
			char[] ch = new char[n];
			for (int i = 0; i < n; i++)
				ch[i] = readChar();
			return ch;
		}
		String readLine() {
			String str = "";
			try {
				str = br.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			}
			return str;
		}
		void close() {
			try {
				br.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}
}
