This is a probability question in Math 370

Craig pays 260 to play an electronic game of chance at a casino. The rules of the game are as follows: The game will randomly simulate a sequence of 20 coin flips. The probability that any given flip comes up as heads is equal to p, and is unknown to Craig. After all 20 flips are generated, the game will pay Craig an amount equal to X, were X is the number of flips resulting in heads. Determine the smallest value of p for which Craig's net expected winnings (including the cost to play) are greater than zero