Write a program to find the maximum and minimum values from a list without using built-in max() or min().

numbers = [23, 5, 67, 12, 99, 34, 8, 76, 1, 50]

maximum = numbers[0]
minimum = numbers[0]

i = 1
while i < len(numbers):
    if numbers[i] > maximum:
        maximum = numbers[i]
    if numbers[i] < minimum:
        minimum = numbers[i]
    i += 1
print("Maximum value is:", maximum)
print("Minimum value is:", minimum)