Older letters of the Russian alphabet include ⟨ѣ⟩, which merged to ⟨е⟩ (/je/ or /ʲe/); ⟨і⟩ and ⟨ѵ⟩, which both merged to ⟨и⟩ (/i/); ⟨ѳ⟩, which merged to ⟨ф⟩ (/f/); ⟨ѫ⟩, which merged to ⟨у⟩ (/u/); ⟨ѭ⟩, which merged to ⟨ю⟩ (/ju/ or /ʲu/); and ⟨ѧ/⟨ѩ⟩⟩, which later were graphically reshaped into ⟨я⟩ and merged phonetically to /ja/ or /ʲa/. The ja or a indicated the pronunciation of a reduced what?