Easy As Jigsaw ABC (Logical Puzzles Series #5)

This puzzle was created in the year 2010 for the 11th 24-Hr Championship. I made a few puzzles of this type for 24 Hr. Championship. However, this puzzle got selected to be part of that championship.

I am now re-publishing this Easy As Jigsaw ABC as 5th puzzle in the Logical Puzzles Series. Can you solve this Easy As Jigsaw ABC puzzle?

Rules of Easy As Jigsaw ABC puzzle

Place letters A-D so that in each row, in each column, in each outlined area, and in the remaining gray cells inside the grid there will exist precisely one of each letter A, B, C, and D. The letters outside the grid indicate the letter seen first in the corresponding direction.