Program 1 will open a named pipe (pick a name) and fork; the child will execute Program 2. In the parent, Program 1 will read from standard input pairs of integers and writes the sum and difference of the integers to the pipe.
Finally it waits for the child to terminate, prints the child's status code, and it terminates.
Program 2 (pick a name) will open the named pipe and read pairs of integers. From these it will recover the original pair the Program 1 read and print the original pair to standard output.
When it sees a pair of zeros, it will terminate and return the status code of the number of [non-zero] pairs it read.