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<math.h>

int main(){
    int x,i,j,k=0,ans,max=0,a[500];
    scanf("%d",&x);
    for(i=1;i<=31;i++){
        for(j=2;j<=10;j++){
            ans=pow((double)i,(double)j);
            if(ans<=x){
                a[k]=ans;
                k++;
            }
        }
    }
    for(i=0;i<k;i++){
        if(max<a[i]){
            max=a[i];
        }
    }
    printf("%d\n",max);
}