Given an array, write a program to find the maximum GCD among all the subarray of the size >= 2 of the given array.
Examples:
Input list: [2, 3, 4, 4, 4] Output: 4 Input list: [3, 7, 2, 9, 18, 5, 1, 13 ] Output: 9
Approach:
 Import the math module for python
 Introduce a variable(say, V1) to store the gcd of each element of the list while looping through the list.
 Iterate through the elements of the array or list using a loop.
 At each iteration call the math.gcd() function.
 Store the outcome of the math.gcd() function to another variable (say, V2) at each iteration.
 Now compare V1 and V2. If V2 is greater than V1, set V1 equal to V2 else pass.
 Let the loop run through and print out the final value of V1.
Below you can find the implementation of the abovementioned approach:
Examples 1:
import math
# input list List = [ 2 , 3 , 4 , 4 , 4 ]
max1 = 0
for i in range ( len ( List )  1 ):
# use math.gcd() function
gcd1 = math.gcd( List [i], List [i + 1 ])
if (gcd1>max1):
max1 = gcd1
# print max1 # as the result print (max1)

Output:
4
Explanation:
For the given array one of the subarrays having maximum gcd is[3, 5] which has gcd 4.
Example 2:
import math
# input list List = [ 3 , 7 , 2 , 9 , 18 , 5 , 1 , 13 ]
max1 = 0
for i in range ( len ( List )  1 ):
# use math.gcd() function
gcd1 = math.gcd( List [i], List [i + 1 ])
if (gcd1>max1):
max1 = gcd1
# print max1 # as the result print (max1)

Output:
9
Explanation:
For the given array one of the subarrays having maximum gcd is[4, 5] which has gcd 9.
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