Exercise 3: Here's the listing for swap_n_add.c: 1 int swap_n_add(int *xp, int *yp) { 2 3 int yyp; 4 int x -*xp; 7 return x + y; 8 10 int main(int argc, char **argv) 11 int a1- 534; 12 int a2 1057; 13 int sum swap_n_add(&a1, &a2); 14 int diff-a1-a2; 15