Answer:
Upward.
Explanation:
Frictional force will prevent you from slipping while walking on the floor. However for the other foot that is moved during a stride, there is a contact force. And the floor is exerting that contact force on the foot in the upward direction while foot exert it on the floor in downward direction when it comes in contact with the floor. That's how we balanced ourselves while walking, running etc. Contact force is also known as the normal force and this force exists wherever the two objects got into contact with other. It's example can be a book on a table, box on the floor, man standing on ground is due to contact force.