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.util.*;
import java.lang.*;

class Main{
  public static void main(String args[]){
    Scanner sc = new Scanner(System.in);
    int x = sc.nextInt();
    int MAX_ROOT = (int)Math.sqrt(x);
    double e = 0;
    double max = e;
    for(int i = 2;i <= MAX_ROOT;i++){
      for(int j = 1;j <= 9;j++){
        e = Math.pow(i,j);
        if(e > x) break;
        if(max < e){
          max = e;
        }
      }
    }
    int emax = (int)max;
    System.out.println(emax);
  }
}