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 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <stdio.h>
#include <stdlib.h>

int main(){
    int a,b,c,d;
    if(scanf("%d",&a)==1);
    if(scanf("%d",&b)==1);
    if(scanf("%d",&c)==1);
    if(scanf("%d",&d)==1);

    int flag=0;
    if(abs(a-c)<=d)flag=1;
    if(abs(a-b)<=d && abs(c-b)<=d) flag=1;

    if(flag==1)printf("Yes\n");
    else printf("No\n");

}