function find_same(first, second, third)
    for c in first:gmatch('.') do
        if string.find(second, c) ~= nil and string.find(third, c) ~= nil then
            return c
        end
    end
end


function priority(char)
    dec = string.byte(char)
    if dec & 0x20 == 0 then
        -- Uppercase
        return dec - string.byte('A') + 27
    else
        -- Lowercase
        return dec - string.byte('a') + 1
    end
end


file = io.open('input')
sacks = {}
for line in file:lines() do
    table.insert(sacks, line)
end

total = 0
for i = 1, math.floor(#sacks / 3) do
    local i0 = i - 1
    local first  = sacks[i0 * 3 + 1]
    local second = sacks[i0 * 3 + 2]
    local third  = sacks[i0 * 3 + 3]

    local same = find_same(first, second, third)
    total = total + priority(same)
    print(same, total)
end

print(total)