#!/usr/bin/python3

# Import lists of the alphabet so we can find indxes later.
from string import ascii_lowercase, ascii_uppercase

commonItems = []
backpacks = []

# Read the whole input file to a list.
with open('input.txt', 'r') as inputFile:
    backpacks = inputFile.readlines()

# Group the backpacks up into threes and find the common item in each three.
currentBackpack = 0
while(currentBackpack < len(backpacks)):
    currentGroup = []
    while(len(currentGroup) < 3):
        currentGroup.append(backpacks[currentBackpack].strip())
        currentBackpack += 1
    for item in currentGroup[0]:
        if(item in currentGroup[1] and item in currentGroup[2]):
            commonItems.append(item)
            break

# For all of the common items we found, total up the priorities.
totalPriority = 0
for item in commonItems:
    if(item in ascii_lowercase):
        totalPriority += (ascii_lowercase.index(item) + 1)
    elif(item in ascii_uppercase):
        totalPriority += (ascii_uppercase.index(item) + 27)

# Print the answer.
print(totalPriority)