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()
{
    int jg,ys,x,i,j,t;
    scanf("%d",&x);
    t=x;ys=0;jg=0;
    for(i=x-1;i>1;i--)
    {
        for(j=2;j<i;j++)
        {
            while(t!=0)
            {
             ys=t%i;
             if(ys!=0)
                    t=0;
                else
                    t=t/i;
            }
        }
            if(ys==0)
            {
                jg=i;break;
            }
    }
    if(jg==0)
        printf("%d\n",jg);
    return 0;
}