from itertools import product

keyboard = {
                 "2": "abc", "3": "def",
    "4": "ghi",  "5": "jkl", "6": "mno",
    "7": "pqrs", "8": "tuv", "9": "wxyz"
}

def comboOf(n):
    return [ "".join(i) for i in product(list("23456789"), repeat=n) ]
