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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <iostream>
using namespace std;
int zyou(int a,int b){
    int c=1;
    for(int i=0;i<b;i++){
        c*=a;
      }
      return c;
}
int main(void){
    int a=1;
    int x;
    cin>>x;
    for(int i=1;i<31;i++){
        for(int j=1;j<9;j++){
            int y=zyou(i+1,j+1);
            if(y<=x){
                a=max(a,y);
            }
        }
    }
    cout<<a<<endl;
}