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 Python (3.4.3) (judge verdict: Accepted)

def getinputdata():

    # 配列初期化
    array_result = []    
    data = input()
    array_result.append(data.split(" "))

    flg = True

    try:
        while flg:

            data = input()

            if(data != ""):
                
                array_result.append(data.split(" "))

                flg = True

            else:

                flg = False
    finally:

        return array_result

arr_data = getinputdata()

x = int(arr_data[0][0])

b = 1
p = 2
maxdata = 1

while b ** p < x:

    chkflg = True

    while chkflg:

        if b ** p <= x:

            if maxdata <= b ** p:
                
                maxdata = b ** p

            b += 1

        else:

            b = 2
            p += 1
            chkflg = False

print(maxdata)