decode = ["afkpuz",
          "bglqv.",
          "chmrw?",
          "dinsx!",
          "ejoty "]
while True:
    try:
        line = raw_input()
    except EOFError:
        break
    if len(line)%2 == 1:
        print "NA"
        continue
    try:
        print "".join(decode[j-1][i-1]
                      for i,j in zip(map(int,line[::2]),map(int,line[1::2])))
    except IndexError:
        print "NA"