Python program to find the longest common sub-string from two given strings

from difflib import SequenceMatcher

a=input('enter first string : ')
b=input('enter second string : ')

c = SequenceMatcher(None,a,b)
match = c.find_longest_match(0, len(a), 0, len(b))
if (match.size!=0):
    print(a[match.a: match.a + match.size]) 
else:
    print('Longest common sub-string not present')