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>
using namespace std;
int main()
{
	int power(int b,int p);
	
	int x,maxv=1;
	cin>>x;
	
	for(int i=2;i<=int(sqrt(x));i++){
		for(int j=2;j<=10;j++){
			if(power(i,j)<=x && power(i,j)>maxv)
			maxv=power(i,j);
		}
	}
	cout<<maxv;
	return 0;
}

int power(int i,int j){
	int ans=1;
	
	for(int k=1;k<=j;k++){
		ans*=i;
	}
	return ans;
}