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 Pascal (FPC 2.6.2) (judge verdict: Accepted)

program Project1;
{$APPTYPE CONSOLE}
uses
  SysUtils,math;
var
  a,h,w,i,j,count,x,y,sw,m,n,b,c,soeji,sum,max,k,d,p:Integer;
  l:array[0..40] of Integer=(1, 4, 8, 9, 16, 25, 27, 32, 36, 49, 64, 81, 100, 121, 125, 128, 144, 169,196,
   216, 225, 243, 256, 289, 324, 343, 361, 400, 441, 484, 512, 529, 576, 625, 676, 729, 784, 841, 900, 961,1000);
  s,s123,s1,s2,s3:string;
  al:string = 'abcdefghijklmnopqrstuvwxyz';
  tf,tfl,tfr:Boolean;
begin
  try
    { TODO -oUser -cConsole メイン : ここにコードを記述してください }
    Readln(x);
    y:=0;

    while True do begin
      if l[y]>x then begin
        Writeln(l[y-1]);
        Readln;
        exit;
      end;
      inc(y);
    end;
    Readln;
  except
    on E: Exception do
      Writeln(E.ClassName, ': ', E.Message);
  end;
end.