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<bits/stdc++.h>
#include<math.h>
using namespace std;
int main(){
	int a,b[10],c;
	memset(b,0,sizeof(b));
	cin>>a;
	for(int j=0;j<10;j++){
		for(int i=1;pow(i,j+2)<=a;i++){
			b[j]=pow(i,j+2);
		}
	}
	for(int k=0;k<9;k++)
	{	
		for(int m=0;m<9;m++){
			if(b[m]<b[m+1]){
				c=b[m+1];
				b[m+1]=b[m];
				b[m]=c;
			}
		}
	}
	cout<<b[0];
}