To satisfy the water requirement of a town with population 50000, a rapid sand filter was needed which will able to produce 12.5 MLD of potable water. Assuming several filter bed to be used with loss of water during backwash as 7% and the rate of filtration as 100 m/day. If diameter and depth filter bed are 5 m and 6 m respectively, the total number of filter bed (including one filter on stand by mode) required will be ______.