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: Accepted)

#include<stdio.h>
#include<stdlib.h>
#include<math.h>
#include<string.h>
int power(int i){
    int a;
    for(a=1;a<=i;a++){
        if(a*a==i){
            return 1;
        }
        else if(a*a*a==i){
            return 1;
        }
        else if(a*a*a*a==i){
            return 1;
        }
        else if(a*a*a*a*a==i){
            return 1;
        }
         else if(a*a*a*a*a*a==i){
            return 1;
        }
    }
    return -1;
}

int main(void){
    int X;
    scanf("%d",&X);
    int i,judge;
    for(i=X;i>0;i--){
        judge=power(i);
        if(judge>0){
            printf("%d",i);
            break;
        }
    }
    return 0;
}