AoC 2024, day 1, part 2 (dc)

# Command: dc -fdc-p2-nosentinel.dc <input 2>/dev/null
# Redirecting the error for popping an empty stack to /dev/null

# Read Input
?
[
    # stack: item2  item1
    d;b 1+ r:b      # b(item2)++
    Sa              # push item1 on stack a
    ? z0<I
] dsIx

# Process
0 La                # item sum
[
    d;b *+          # sum += b(item) * item
    La z1<L
] dsLx

[Part 2: ]np