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 JavaScript (node.js v5.12) (judge verdict: Accepted)

function main(input) {
  input=input.trim();
  const x = parseInt(input.split("\n")[0], 10);
  var arr=[]
  for(var i=0; i<32; i++){
    arr.push((i+1)*(i+1))
  }
  for(var i=0; i<10; i++){
    arr.push((i+1)*(i+1)*(i+1))
  }
  for(var i=0; i<5; i++){
    arr.push((i+1)*(i+1)*(i+1)*(i+1))
  }
  arr.push(32,243,64,729,128,256,512)
  arr.sort(function(a,b){
    if( a < b ) return -1;
    if( a > b ) return 1;
    return 0;
  });
  for(var i=0; i<arr.length; i++){
    if(arr[i]<=x){
      ans=arr[i]
    }else{
      break
    }
  }
  console.log(ans);

}


main(require('fs').readFileSync('/dev/stdin', 'utf8'));