#!/usr/bin/env python3

# Mainly used for problem development

# Run as full.py --full to generate 10 different instances that aren't impossible
# and that kill the greedy solution

# Add --q to generate instance that kill solutions who ignore that Q is weird


import random
import sys

letters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'

def before(a, b):
    if a == "Q":
        return b >= "U"
    return a <= b

def ignore_q(a, b):
    return a <= b

def solve(lines, comparator=before):
    front = lines[0]
    sides: list[set[str]] = [set() for _ in range(16)]
    for line in lines[1:5]:
        for i, l in enumerate(line):
            sides[i].add(l)
    back = lines[-1]


    # best[c] = smallest number or rotations to sort the
    # current prefix such that it ends in c. If this is impossible, None.
    best = [ (0, front[0]), (2, back[0]) ]  + [(1, letter) for letter in sides[0] if letter != front[0]]
    for i in range(1, 16):
        new_best = []
        for letter, delta in [(front[i], 0)] + [(side, 1) for side in sides[i]] + [(back[i], 2)]:
            for turns, prefix in best:
                if comparator(prefix[-1], letter):
                    new_best.append((turns + delta, prefix + letter))
        best = new_best
    if best:
        return(min(best))
    else:
        return('impossible')


def greedy(lines):
    prefix = '@' # '@' < 'A'
    turns = 0
    for i in range(16):
        vals = [(0, lines[0][i])] + [(2, lines[5][i])] + [(1, lines[j][i]) for j in [1,2,3,4]]
        filtered_vals = list(t[::-1] for t in vals if t[1] >= prefix[-1])
        if not filtered_vals:
            return 'impossible'
        c, t = min(filtered_vals)
        prefix += c
        turns += t
    return turns, prefix


dice = [list(faces) for faces in (
    "AACIOT",
    "ABILTY",
    "ABJMOQ",
    "ACDEMP",
    "ACELRS",
    "ADENVZ",
    "AHMORS",
    "BIFORX",
    "DENOSW",
    "DKNOTU",
    "EEFHIY",
    "EGKLUY",
    "EGINTV",
    "EHINPS",
    "ELPSTU",
    "GILRUW",
    )
]

if '--full' in sys.argv:
    random.seed(0)

    for i in range(10):
        while True:
            random.shuffle(dice)
            for i in range(16):
                random.shuffle(dice[i])
            lines = []
            for i in range(6):
                lines.append(''.join(dice[j][i] for j in range(16)))
            res = solve(lines)
            res_ignore = solve(lines, ignore_q)
            greedy_res = greedy(lines)
            if res != 'impossible' and greedy_res[0] != res[0] and res[0] != res_ignore[0]:
                if 'Q' in res[1] or '--q' not in sys.argv:
                    break
        print(*lines, sep='\n')
        print(res)
        print(res_ignore)
        print(greedy(lines))


else:
    res = solve([input() for _ in range(6)])
    if isinstance(res, str):
        print(res)
    else:
        print(res[0])