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 9.2.1) (judge verdict: Accepted)

#include <stdio.h> 
#include <math.h>
int main(void) 
{ 
    int x, b=1, p, n, m=0;
    
    scanf("%d", &x);
    
    if(x==1){
        printf("1\n");
        return 0;
    }
    
    while(1){
        b++;
        p=2;
        while(x>=pow(b,p)){
            n=pow(b,p);
            p++;
        }
        if(n>m) m=n;
        if(p==2) break;
    }
    printf("%d\n",m);
	return 0;
}