decode = ["afkpuz",
          "bglqv.",
          "chmrw?",
          "dinsx!",
          "ejoty "]
while True:
    try:
        line = map(int,list(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(line[::2],line[1::2]))
    except:
        print "NA"