function readLinesFromFile(file)
    local fs = assert(io.open(file, "rb"))
    local content = fs:read("*all")
    local lines = {}

    fs:close()

    for line in content:gmatch("[^\r\n]+") do
        table.insert(lines, line)
    end

    return lines
end

function tablelength(table)
    local count = 0

    for _ in pairs(table) do
        count = count + 1
    end

    return count
end

function groupByCharacter(word)
    local temp = {}

    for j = 1, string.len(word) do
        local character =  string.sub(word, j, j)

        if temp[character] == nil then
            temp[character] = 0
        end

        temp[character] = temp[character] + 1
    end

    return temp
end

function containsValue(dict, value)
    for k, v in pairs(dict) do
        if v == value then
            return true
        end
    end

    return false
end

function main()
    local words = readLinesFromFile("input.txt")

    local twos = 0
    local threes = 0

    for i = 1, tablelength(words) do
        local word = words[i]
        local occurences = groupByCharacter(word)

        if containsValue(occurences, 2) then
            twos = twos + 1
        end

        if containsValue(occurences, 3) then
            threes = threes + 1
        end
    end

    local checksum = twos * threes

    print(checksum)
end

main()