# Given 2 strings, a and b, return the number
# of the positions where they contain the
# same length 2 substring. So "xxcaazz" and
# "xxbaaz" yields 3, since the "xx", "aa",
# and "az" substrings appear in the same
# place in both strings.
#
#
# string_match('xxcaazz', 'xxbaaz') → 3
# string_match('abc', 'abc') → 2
# string_match('abc', 'axc') → 0

def string_match(a, b):

    count = 0
    short = min(len(a), len(b))

    for i in range(short-1):
        sub_a = a[i:i+2]
        sub_b = b[i:i+2]
        if sub_a == sub_b:
            count += 1
    return count


print(string_match('xxcaazz', 'xxbaaz'))
