#!/usr/bin/python3

import re

def is_number(test):
    pattern = re.compile(r'^(1 roczek)|(2 latka)|(3 latka)|(4 latka)|(\d{1,2} (lat))$')
    
    result = re.match(pattern, test)
    if result:
        return "yes"
    else:
        return "no"

for line in sys.stdin:
	print(is_number(line))