Between the Sheets EV

[cardsharkk04]

In the game Between the Sheets a person will flip up two cards side by side (lets say a Q and a 3) and then you can wager an amount (up to the size of the pot) that the next card will fall in between those two cards. If you win you take that much from the pot, if the next card is higher than a Q or lower than a 3 then you put the amount of your wager in the pot. The only catch is that if the third card is Q or a 3, then you put in double what you wager. How big should the gap be in between the two initial cards in order for a bet to be +EV??