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 C (GCC 5.4.1) (judge verdict: Wrong Answer)

#include<stdio.h>

int pw(int a,int b){
	int ans=1;
	for(int l=1;l<=b;l++){
		ans=ans*a;
	}
	return ans;
}

int main(){
	int X=0;
	int ans,max=1;
	scanf("%d",&X);
	for(int l=0;l<=400;l++){
		for(int l2=0;l2<=100;l2++){
			ans=pw(l,l2);
			if(ans>max&&ans<X){max=ans;}
		}
	}
	printf("%d",max);
	return 0;
}