Red Army and Blue Army should decide whether to attack or defend territories. Decisions are made without knowledge of opposing army's decision in the zero-sum game. Red Army will gain three territories if both armies decide to attack. Red Army will gain five territories if it makes decision to attack and Blue Army makes decision to defend. On other hand, Red Army will gain four territories if it makes decision to defend and Blue Army makes decision to attack. Red Army will gain nothing if both armies make decision to defend their territories. Determine optimal strategy for every army?