3 pipes are connected with a water tank of 4000 liter capacity. 1st and 2nd pipe fill the tank in 10 and 20 minutes individually. The 3rd pipe can empty the tank in 5 minutes. 1st and 2nd pipe was opened together at 10 am. The 3rd pipe was opened after 7 minutes. How much water will there be in tank at 10:26 am?