#!/usr/bin/python3
import sys
import re

def is_number(test):
    pattern = re.compile(r'^((1 roczek)|([2-4] (lata|latka))|(([5-9]|(1[0-9])|20|21) lat)|((([2-9][2-4])|10[2-4]) lata)|(([2-9](156789)|10[0-1]|10[5-9]|110) lat))$')
    
    result = re.match(pattern, test)
    if result:
        return "yes"
    else:
        return "no"

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