decode = ["afkpuz",
          "bglqv.",
          "chmrw?",
          "dinsx!",
          "ejoty "]

def check(i,j):
    return 0<=i<=5 and 0<=j<=4

while True:
    try:
        line = raw_input()
    except EOFError:
        break
    if len(line)%2 == 1:
        line += "9"
    ans = ""
    for i,j in zip(line[::2],line[1::2]):
        i,j = int(i)-1,int(j)-1
        if not check(i,j):
            print "NA"
            break
        ans += decode[j][i]
    else:
        print ans