# Lab_7_Exercise_1_Problem_7_b.py

# b) This function addss the digits contained in a string, if any.

def fun(aString):
    if len(aString) == 1 :
        if aString.isdigit(): 
           result = int(aString)
        else:
           result = 0
    else:
        if aString[0].isdigit():
            result = int(aString [0]) + fun(aString[1:])
        else:
            result = fun(aString[1:])
    return result

# Main part of the program 
# aString = input("Enter the string with which you would like to have fun: ")

# Test Case 1
aString = "358"
result = fun(aString)
print("The function fun({0}) produces = {1}".format(aString, result))

# Test Case 2
aString = "abc"
result = fun(aString)
print("The function fun({0}) produces = {1}".format(aString, result))

# Test Case 3
aString = "a3c2$"
result = fun(aString)
print("The function fun({0}) produces = {1}".format(aString, result))