How can the MARIE processor be used to count the number of zeroes in user input?

[twoski]

Homework Statement

Write a MARIE program that repeatedly receives a sequence of decimal digits (one digit at a time) and counts the number of occurrences of ‘0’ and stores it in memory location Count until a non-digit is received. Assemble and run your program using the MARIE simulator

Homework Equations

http://www.edwardbosworth.com/CPSC2105/Lectures/Slides_05/Chapter_04/MARIE_Organization.htm

The Attempt at a Solution

I start with reading user input, but how do i check how many zeroes are in the input if i can only add/subtract values?

 

[rcgldr]

I start with reading user input, but how do i check how many zeroes are in the input if i can only add/subtract values?

The MARIE processor also has a SKIPCOND instruction, how could you make use of that?