from string import ascii_letters

sum_of_priorities = 0

with open("3.in") as fh:
    for backpack in fh:
        backpack = backpack.strip()

        comp_size = len(backpack)//2

        comp_a = set(backpack[comp_size:])
        comp_b = set(backpack[:comp_size])

        item_in_both = list(comp_a.intersection(comp_b))[0]
        priority = ascii_letters.find(item_in_both) + 1
        sum_of_priorities += priority

print(sum_of_priorities)