def isApproxMatch(a, b, k):
    """Return True if equal-length strings a and b have at most k mismatches."""
    # your code here!



def findApprox(strand, pattern, k):
    """
    Return the first index at which an approximate match to the pattern begins
    in the given strand, or return -1 if no such match is found.

    An approximate match is one that has at most k mismatched characters.
    """
    # your code here!






#########################################################
# Do not make any changes to what follows.
#########################################################

for line in open('tests.txt'):
    pieces = line.split()
    if pieces:
        if len(pieces) != 3:
            print('Ignoring line: %s' % line)
        elif not pieces[2].isdigit():
            print('Illegal choice of k: %s' % line)
        else:
            print('Executing findApprox(%s,%s,%s)...' % tuple(pieces))
            print('  returned: %s' % (findApprox(pieces[0], pieces[1], int(pieces[2]))))