SNAP 2017 Time and Work — Previous Year Question

An Olympic size swimming pool requires 6 hours to fill up to the brim when water is supplied simultaneously by three pipes A, B and C. The pipes start filling at 12 o'clock in the night but if pipe C is shut off at 3 am, the swimming pool fills up to the brim at 7 am. The swimming pool is drained in the evening. That night, if only pipe C is used to fill up the swimming pool and the filling starts at 12 o'clock in the night, what will be the time in the clock when the swimming pool will be filled up to the brim?