import re

def isChar(n):
    return re.match(r'[a-z]', str(n)) is not None

def isNumber(n):
    return re.match(r'\d+', str(n)) is not None

def getPrecedence(tok):
    if tok == "(" or tok == "" or tok == "^":
        return 4
    elif tok == "*" or tok == "/":
        return 3
    elif tok == "+" or tok == "-":
        return 2