
    A delivery fleet manager needs to calculate the total number of deliveries possible throughout different time slots in a day, accounting for gradual vehicle unavailability. Starting with an initial fleet size, pairs of vehicles become unavailable in subsequent time slots due to mandatory maintenance breaks. For each time slot, the number of available vehicles decreases by 2 from the previous slot, and this pattern continues until no vehicles are available. Given the initial fleet size, calculate the sum of available vehicles across all affected time slots to determine the total delivery capacity for the day.
    

    
def sum_series(n):
    """
    A delivery fleet manager needs to calculate the total number of deliveries possible throughout different time slots in a day, accounting for gradual vehicle unavailability. Starting with an initial fleet size, pairs of vehicles become unavailable in subsequent time slots due to mandatory maintenance breaks. For each time slot, the number of available vehicles decreases by 2 from the previous slot, and this pattern continues until no vehicles are available. Given the initial fleet size, calculate the sum of available vehicles across all affected time slots to determine the total delivery capacity for the day.
    

    """
def sum_series(n):
    """
    A delivery fleet manager needs to calculate the total number of deliveries possible throughout different time slots in a day, accounting for gradual vehicle unavailability. Starting with an initial fleet size, pairs of vehicles become unavailable in subsequent time slots due to mandatory maintenance breaks. For each time slot, the number of available vehicles decreases by 2 from the previous slot, and this pattern continues until no vehicles are available. Given the initial fleet size, calculate the sum of available vehicles across all affected time slots to determine the total delivery capacity for the day.
    

    """
    if n < 1:
        return 0
    else:
        return n + sum_series(n - 2)