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 main() {
	long long int n, s[1001] = {},m,count=0;
  	scanf("%lld",&n);
	for (int i = n; i >= 1; i--) {
		m = i;
      
      	for (int k = 2; k <= 1000; k++) {
			s[k]=0;
		}
		for (int j = 2; j <= 1000; j++) {
			for (int k = 1; k <= 10; k++) {
				if (m%j == 0) {
					s[j]++;
                  	m=m/j;
				}
			}

			
		}

		for (int k = 2; k <= 1000; k++) {
			if (s[k] == 1) {
				goto next;
			}
		}
		printf("%lld", i);
      	return 0;
		next:
		count++;
	}
}