In a skillet, cook beef, onion, salt and pepper over medium heat until meat is no longer pink; drain. Add tomato sauce, corn, tomatoes, half of the olives and the chili powder. Bring to a boil. Reduce heat; cover and simmer for 30 minutes. In a greased 13-in. x 9-in. baking dish, layer half of the meat mixture, cheese and tortillas. Repeat layers. Sprinkle with remaining olives. cover and bake at 350° for 30 minutes. Uncover and bake 15 minutes longer or until heated through. Yield: 8 servings.