A painter places a 13 m long regular ladder against a vertical wall with negligible friction. The ladder's lower end is 5 m from the wall. Take the weight of the ladder to be 250 N and the coefficient of static friction between the floor and the ladder's foot to be 0.65. If a painter weighing 650 N climbs gently up the ladder, determine the maximum friction force that the floor can apply on the ladder's lower end.