import sys


def isCorrect(line):
    line = line.rstrip('\n')

    stan = stan0
    koncowe = {stan0: 'nie', stan1: 'nie', stan2: 'tak', stan3: 'nie'}
    for char in line:
        stan = stan(char)
    print(koncowe[stan])


def stan0(char):
    if char == 'a':
        return stan1
    if char == 'b':
        return stan3


def stan1(char):
    if char == 'a':
        return stan1
    if char == 'b':
        return stan2


def stan2(char):
    if char == 'a':
        return stan0
    if char == 'b':
        return stan3


def stan3(char):
    if char == 'a':
        return stan3
    if char == 'b':
        return stan3


# isCorrect('ab')
for line in sys.stdin:
    isCorrect(line)