Rather than pen and paper I recommend using a computer if you have access to one.

   (-⟜»∘⍷∧)⍟(1+↕3) 11‿39‿23‿28‿31‿19‿32‿5‿1‿9

⟨ ⟨ 1 4 4 2 8 4 5 3 1 7 ⟩ ⟨ 1 1 1 1 1 2 1 ⟩ ⟨ 1 1 ⟩ ⟩

   -⟜»∘⍷∧ vec

⟨ 7 2 4 1 3 2 2 4 10 12 3 10 1 6 1 5 17 2 8 ⟩

   +´-⟜»∘⍷∧ vec

100

   ⍷∧ vec

⟨ 7 9 13 14 17 19 21 25 35 47 50 60 61 67 68 73 90 92 100 ⟩

   +`-⟜»∘⍷∧ vec

⟨ 7 9 13 14 17 19 21 25 35 47 50 60 61 67 68 73 90 92 100 ⟩