def getChange(amount, curr, left):
    if sum(curr) == amount:
        return curr
    elif sum(curr) < amount:
        for x in left:
            res = getChange(amount, curr | {x}, left - {x})
            if len(res) > 0:
                return res
            else:
                return set()
    else:
        return set()

print(getChange(26, set(), regis))