file = io.open("input")
io.input(file)

score = 0
data = {}

for line in file:lines() do
    table.insert(data, line)
end

for i = 1, #data/3 do
    local one = data[(i-1)*3+1]
    local two = data[(i-1)*3+2]
    local three = data[(i-1)*3+3]

    for n = 1, #one do
        local char = string.sub(one, n, n)
        if string.match(two, char) and string.match(three, char) then
            if char == string.upper(char) then
                score = score + string.byte(char) - string.byte("A") + 27
                goto continue
            elseif char == string.lower(char) then
                score = score + string.byte(char) - string.byte("a") + 1
                goto continue
            end
        end

    end

    ::continue::
end

print(score)