Throughout the game, you will find several storehouses of food (Where you'll find items like Instant Noodles and Calorie Mates) and ammunition (Often where you find new weapons). If you have some TNT in your inventory, plant a piece inside a storehouse, stand back, and detonate it. You'll know the trick worked if the room becomes charred and black. If you do this to a food storehouse, enemies in the nearby screens will complain about their hunger, helping you detect them easily. If you destroy an ammo warehouse, guards will have only one clip of AK ammo, then they will switch to a pistol, and eventually they will have to use a knife.