if __name__ == "__main__": str_in = list(map(int, input().split())) lifts_count = str_in[0] groups_count = str_in[1] lift_size = str_in[2] lift_time = str_in[3] people_arrived = [0]*50; arrivals = [list()]*groups_count for i in range(0, groups_count): group = list(map(int, input().split())) group_arrive = group[0] #less or equal to 50 group_size = group[1] people_arrived[group_arrive] = group_size arrivals[i] = group for i in range(1, 50): people_arrived[i] = people_arrived[i-1] + people_arrived[i] total_people = people_arrived[49] ## Tuples (Time of waiting, Amount of people) waiters = list() people_transported = 0 current_arrival = 0 ##Number of group, man from which is first in queue next_transport = [0]*lifts_count available_lift = 0 while people_transported < total_people: sec = next_transport[available_lift] people_waiting = people_arrived[min([sec, 49])] - people_transported if people_waiting <= 0: sec = arrivals[current_arrival][0] people_waiting = people_arrived[sec] - people_transported ##Here we know for sure, that there is free lift, and there is people ##in queue people_sent_now = min(lift_size, people_waiting) people_transported = people_transported + people_sent_now print('lift', available_lift, 'will run at sec', sec, 'with',people_sent_now, 'people') while current_arrival < groups_count and arrivals[current_arrival][1] <= people_sent_now: waiters.append((arrivals[current_arrival][1], sec-arrivals[current_arrival][0])) people_sent_now = people_sent_now - arrivals[current_arrival][1] current_arrival = current_arrival+1 if(current_arrival < groups_count): waiters.append((people_sent_now, sec-arrivals[current_arrival][0])) arrivals[current_arrival][1] = arrivals[current_arrival][1] - people_sent_now ##Updating info about lifts next_transport[available_lift] = sec + lift_time*2 available_lift = (available_lift+1)%lifts_count #print(waiters) time_waiting = 0 for i in range(0, len(waiters)): time_waiting = time_waiting + waiters[i][0]*waiters[i][1] print(lift_time + time_waiting/total_people)