#!/usr/bin/env python3

# Inspired by descriptive part of oldest answer in
# https://stackoverflow.com/questions/23308954

def try_flips(Outlets, Devices, nDev, l):

    # Try all the devices in all the outlets

    # Find the flip configurations in bitwise form
    # that are compatible (present) in all the outlets

    S = set()
    for j in range(len(Devices)):
        S.add(Outlets[0] ^ Devices[j])

    for i in range(1, len(Outlets)):
        row = set()
        for j in range(len(Devices)):
            row.add(Outlets[i] ^ Devices[j])
        S = S.intersection(row)

    # If no common configuration is found, then no flip can
    # solve this case

    if len(S) == 0:
        return "NOT POSSIBLE"

    # Otherwise, pick the one with the smallest number of 1s
    # (which represent flips) and return the number of flips

    m = None
    for s in S:
        b = count_bits(s)
        if m is None or b < m:
            m = b
    return str(m)


def count_bits(x):
    i = 0
    while x != 0:
        i = i + (x & 1)
        x = x >> 1
    return i


def read_switches():
    O = input().split()
    for i in range(len(O)):
        O[i] = int(O[i], 2)
    return O


if __name__ == "__main__":
    t = int(input())

    for i in range(t):
        line = input().split()
        n, l = int(line[0]), int(line[1])

        Outlets = read_switches()
        Devices = read_switches()

        print("Case #" + str(i + 1) + ": " + try_flips(Outlets, Devices, n, l))