import sys

stdout = sys.stdout.buffer

ix = 0
for line in sys.stdin:
    words = line.split()
    for word in words:
        if ';' in word:
            break
        else:
            if word == '??':
                print(f'?? at {ix:02x}', file=sys.stderr)
                number = 0xff
            else:
                number = int(word, 16)
            assert number < 256
            stdout.write(bytes([number]))
            ix += 1;