# reads in a list of numbers, prints the number of positive numbers
# ECS 10, May 29, 2009
# Matt Bishop

# read in a list of comma-separated numbers from the input
# parameters: none
# returns: 2 values
#     1st: the list, if read successfully; empty list, if not
#     2nd: True, if list read successfully; False, if not
def getlist():
    # read the input
    # catch any problems and bail out at once
    try:
        inp = input("Enter a comma-separated sequence of numbers: ")
    except (EOFError, TypeError, NameError, SyntaxError):
        return [], False
    # now check each element is a number
    # we actually build the list here
    lst = []
    for i in inp:
        # number check: if adding 0 causes a TypeError,
        # it's not a number and we skip it (with a
        # suitable error message)
        try:
            i += 0
        except TypeError:
            print i, "is not a number -- ignoring it"
        else:
            # it's a number -- add it to the list
            lst.append(i)
    # return results
    return lst, True

# recursively count the number of positive integers in the list
# parameters: lst, the list
# returns: the number of positive integers in the list
def poslist(lst):
    # base case: empty list has 0 positive elements
    if lst == []:
        return 0
    # recursion here
    elif lst[0] > 0:
        # positive number: one more than are in rest of list
        return 1 + poslist(lst[1:])
    else:
        # non-positive number: same as in the 
        return poslist(lst[1:])

# this puts it all together
def main():
    # read in the list
    lst, okay = getlist()
    # if a valid list eas read, count the number
    # of positive elements in it
    if okay:
        print "There are", poslist(lst), "positive numbers in your list"

main()