def problem1_3(n):
    my_sum = 0
    for i in range(n,0,-1):
        my_sum=my_sum+i
    print(my_sum) 
def problem1_3(n):
    my_sum = 0
    for i in range(n,0,-1):
        my_sum=my_sum+i
    print(my_sum) 