Solve clearly

Two firms, Tim Horbucks and Startons, consider enter the market for take-out coffee, or not. The profit each firm can make (in dollars) is indicated in the table below, where the fixed cost of producing is F dollars. What is the largest value of F below which the game has a UNIQUE Nash equilibrium in pure strategies? Startons Enter Not Enter Enter 200 - F, 200 - F 800 - F , O Tim Horbucks Not Enter 0, 800 - F 0,0 Enter a positive number below, in dollars