Are the big four exercises enough?

By big four I mean push-ups, pull-ups, dips and squats. I'm 16, haven't worked out for more than a month straight, my goal is to build good strength and muscle. I'm not aiming for anything super, as I'm also going to do some endurance, skill training and some martial arts to be a well rounded human being, but I want to keep things simple so I can stay disciplined to push through with my workouts. So, are they enough for strength training, if not what advice do you have for me regarding discipline?