a = ["alpha", "beta", "gamma"]
b = ["a", "b", "c", "d"]
c = ["one", "two", "three", "four", "five"]

def mapping():
    i = 0
    key = {}
    for _a in a:
        for _b in b:
            for _c in c:
                key["-".join([_a, _b, _c])] = i
                i += 1
    return key

key = mapping()
reverse = {v: k for k, v in key.items()}

num1 = key["alpha-b-two"]
num2 = key["alpha-a-four"]
print(num1-num2)

print(reverse[key["alpha-a-four"] + 3])