The coefficient of static friction is 0.604 between two blocks. The coefficient of kinetic friction between the lower block and the floor is 0.115. Force F causes both blocks to cross a distance of 3.93 m, starting from rest. What is the least amount of time in which the motion can be completed without the top block sliding on the lower block, if the mass of the lower block is 1.03 kg and the mass of the upper block is 3.04 kg?