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') 

Python program to find the first non-repeating character in given string

a = input('Enter a string : ')
char_order = []
ctr = {}
for c in a:
    if c in ctr:
      ctr[c] += 1
    else:
      ctr[c] = 1
      char_order.append(c)
for c in char_order:
    if ctr[c] == 1:
        print(c)
        break