moons = {}
for line in io.lines(arg[1]) do
    x, y, z = line:match("<x=(-?%d+), +y=(-?%d+), +z=(-?%d+)>")
    table.insert(moons, {pos={x=tonumber(x), y=tonumber(y), z=tonumber(z)}, vel={x=0, y=0, z=0}})
end

function update_vel(moon)
    for _, omoon in ipairs(moons) do
        for _, axis in ipairs({"x", "y", "z"}) do
            if omoon.pos[axis] > moon.pos[axis] then
                moon.vel[axis] = moon.vel[axis] + 1
            end
            if omoon.pos[axis] < moon.pos[axis] then
                moon.vel[axis] = moon.vel[axis] - 1
            end
        end
    end
end

function update_pos(moon)
    moon.pos.x = moon.pos.x + moon.vel.x
    moon.pos.y = moon.pos.y + moon.vel.y
    moon.pos.z = moon.pos.z + moon.vel.z
end

print("After 0 steps:")
for _, moon in ipairs(moons) do
    print(string.format("pos=<x=%d, y=%d, z=%d>, vel=<x=%d, y=%d, z=%d>", moon.pos.x, moon.pos.y, moon.pos.z, moon.vel.x, moon.vel.y, moon.vel.z))
end
print()
for i = 1, 10 do
    for _, moon in ipairs(moons) do
        update_vel(moon)
    end

    for _, moon in ipairs(moons) do
        update_pos(moon)
    end

    print(string.format("After %d steps:", i))
    for _, moon in ipairs(moons) do
        print(string.format("pos=<x=%d, y=%d, z=%d>, vel=<x=%d, y=%d, z=%d>", moon.pos.x, moon.pos.y, moon.pos.z, moon.vel.x, moon.vel.y, moon.vel.z))
    end
    print()
end

energy = 0
for _, moon in ipairs(moons) do
    pot = math.abs(moon.pos.x) + math.abs(moon.pos.y) + math.abs(moon.pos.z)
    kin = math.abs(moon.vel.x) + math.abs(moon.pos.y) + math.abs(moon.pos.z)
    energy = energy + pot * kin
end
print("Energy:", energy)