def find_tribonacci(n):
    # if n is less than 3, then it's the base case
    if n < 3:
        return 1 if n else 0

    # initializing first three numbers
    first_num, second_num, third_num = 0, 1, 1
    # loop proceeds for n-2 times
    for _ in range(n - 2):
        # compute the sum of the last three Tribonacci numbers and update
        # first_num, second_num and third_num for the next iteration
        first_num, second_num, third_num = second_num, third_num, \
          first_num + second_num + third_num
    return third_num


# Driver code
def main():
    n = [4, 5, 25, 17, 19]
    for i in range(len(n)):
        print((i + 1), ".\tThe ", (n[i]), "th Tribonacci number is:  ",
              find_tribonacci(n[i]), sep="")
        print("-"*100, "\n")


if __name__ == '__main__':
    main()