Three persons A, B and C start traveling from city P at 1:00 a.m., 2:00 a.m. and 3:00 a.m. respectively. All the three reach the point Q simultaneously and continue beyond that point. C reaches the point R first and turns back immediately towards P. Thirty minutes after turning back, he crosses A.

If the distance between P and Q is equal to the distance between Q and R, then the time at which all the three reach Q is