There is a differentiated Stackelberg duopoly. The inverse demand curve for the first mover is p subscript 1 equals a minus 2 q subscript 1 minus q subscript 2 and the inverse demand for the second mover is p subscript 2 equals a minus 2 q subscript 2 minus q subscript 1, where a=7. There are no costs of production. The quantity that the first mover will choose in a subgame perfect equilibrium is: