Problem:
Score : 200 points

Problem Statement

You are given a positive integer X.
Find the largest perfect power that is at most X.
Here, a perfect power is an integer that can be represented as b^p, where b is an integer not less than 1 and p is an integer not less than 2.

Constraints

1 ≤ X ≤ 1000

X is an integer.

Input

Input is given from Standard Input in the following format:

X

Output

Print the largest perfect power that is at most X.

Sample Input 1

10

Sample Output 1

9

There are four perfect powers that are at most 10: 1, 4, 8 and 9.
We should print the largest among them, 9.

Sample Input 2

1

Sample Output 2

1

Sample Input 3

999

Sample Output 3

961

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {

	public static void main(String[] args) throws NumberFormatException, IOException {
		// TODO 自動生成されたメソッド・スタブ
		BufferedReader vd = new BufferedReader(new InputStreamReader(System.in));
		int x = Integer.parseInt(vd.readLine());
		
		int max=0;
		for(int i=0;i<32;i++) {
			for(int j=0;j<10;j++) {
				int p = (int)Math.pow(i, j);
				if(p<=x&&p>max) {
					max= p;
				}
			}
		}
		System.out.println(max);
	}

}