width = tonumber(arg[2])
height = tonumber(arg[3])

layers = {}
layer = {}
row = {}
for x in io.open(arg[1]):read("a"):gmatch("%d") do
    table.insert(row, tonumber(x))
    if #row >= width then
        table.insert(layer, row)
        row = {}
        if #layer >= height then
            table.insert(layers, layer)
            layer = {}
        end
    end
end
layer = nil
row = nil

fewest = nil
for layer_index, layer in ipairs(layers) do
    count = 0
    for _, row in ipairs(layer) do
        for _, pixel in ipairs(row) do
            if pixel == 0 then
                count = count + 1
            end
        end
    end

    if not fewest or count < fewest[1] then
        fewest = {count, layer_index}
    end
end

result_p1 = {0, 0}
for _, row in ipairs(layers[fewest[2]]) do
    for _, pixel in ipairs(row) do
        if not result_p1[pixel] then
            result_p1[pixel] = 0
        end
        result_p1[pixel] = result_p1[pixel] + 1
    end
end

print("Part 1:", result_p1[1] * result_p1[2])

if not arg[4] then
    os.exit(true)
end

output = io.open(arg[4], "w")
output:write(string.format("P1\n%d %d\n", #layers[1][1], #layers[1]))
for row_index, row in ipairs(layers[1]) do
    for pixel_index, pixel in ipairs(row) do
        if pixel == 2 then
            for x = 2, #layers do
                pixel = layers[x][row_index][pixel_index]
                if pixel ~= 2 then
                    break
                end
            end
        end
        output:write(pixel)
        output:write(" ")
    end
end