local file = io.open("input.txt")
local contents = file:read("*l")
local priority = 0

function table.contains(table, element)
    for _, value in pairs(table) do
        if value == element then
            return true
        end
    end
    return false
end

while contents do
    local len = string.len(contents)
    local comp1 = {}
    string.gsub(string.sub(contents, 1, len / 2 + 1), ".",function(c) table.insert(comp1,c) end)
    local comp2 = {}
    string.gsub(string.sub(contents, len / 2 + 1, len), ".",function(c) table.insert(comp2,c) end)

    for _, v in ipairs(comp1) do 
        if table.contains(comp2, v) then
            priority = priority + string.byte(v)
            break
        end
    end

    contents = file:read("*l")
end

print(priority)