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 Go (1.14.1) (judge verdict: Accepted)

package main

import (
	"fmt"
	"math"
)

func main() {
	// Code for B - Exponential
	var X int
	fmt.Scanf("%d", &X)

	if X == 1 {
		fmt.Println("1")
	} else {
		var max int
		for b := 1; b < X; b++ {
			for p := 2; p < 100; p++ {
				A := int(math.Pow(float64(b), float64(p)))
				if A > X {
					break
				} else {
					if max < A {
						max = A
					}
				}
			}
		}
		fmt.Println(max)
	}
}