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 X,i,n,j,N;
    scanf("%d",&X);
    for(i=X;i>0;i--){
        if(X==1){
            printf("%d",1);
            return 0;
        }
       for(n=2;n<35;n++){
           N=i;
           while(N>n){
               if(N%n==0){
                   N=N/n;
               }
               else{
                   break;
               }
               }
               if(N==n){
                   printf("%d",i);
                   return 0;
           }
       } 
    }
    return 0;
}