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: Wrong Answer)

#include <bits/stdc++.h>
#define rep( i, n ) for( int ( i ) = 0; ( i ) < ( n ); ( i )++ )
#define repr( i, n ) for( int ( i ) = ( n ); ( i ) >= 0; ( i )-- )
#define FOR( i, m, n ) for( int ( i ) = ( m ); ( i ) < ( n ); ( i )++ )
#define all( x ) ( x ).begin(), ( x ).end()
typedef long long lint;
using namespace std;
 
int main( void ){
	
	int x;
	int ans;
	lint i,j;
	int temp;
	cin >> x;
	
	for( i = x; i > 0; i-- ){
		temp = i;
		for( j = 10; j > 0; j-- ){
			temp *= i;
			if( temp <= x && temp > 0){
				cout << temp << endl;
				return 0;
			}
		}
	}
	
	return 0;
}