def minimum_platform(arrival_time, departure_time, size):
    """
    Given arrival and departure times of all trains that reach a railway 
    station, find the minimum number of platforms required for the railway 
    station so that no train waits.
    """
    print(arrival_time, departure_time, size)
    platform_count = 1
    if size < 1:
        return 0
    i = 1
    j = 0
    while i < size and j < size:
        if arrival_time[i] >= departure_time[j]:
            i += 1
            j += 1
        else:
            i += 1
            platform_count += 1
    return platform_count