Structures, Unions, Enums - General Questions

What will be the output of the program?

#include <stdio.h>
struct N { int v; struct N *next; };
int main(void) {
    struct N c = {3, NULL}, b = {2, &c}, a = {1, &b};
    int s = 0;
    struct N *p;
    for (p = &a; p; p = p->next) s += p->v;
    printf("%d\n", s);
    return 0;
}

What will be the output of the program?

#include <stdio.h>
struct P { int a; int b; };
int main(void) {
    struct P p = {1, 2}, q;
    q = p;
    q.a = 9;
    printf("%d %d\n", p.a, q.a);
    return 0;
}

What will be the output of the program?

#include <stdio.h>
enum { A = 10, B = 5, C };
int main(void) {
    printf("%d\n", A + C);
    return 0;
}

What will be the output of the program?

#include <stdio.h>
struct Point { int x, y; };
int main(void) {
    struct Point p = {3, 4};
    struct Point *q = &p;
    q->x = 10;
    printf("%d %d\n", p.x, q->y);
    return 0;
}

What will be the output of the program?

#include <stdio.h>
union U { int i; unsigned char b[4]; };
int main(void) {
    union U u;
    u.i = 0;
    u.b[0] = 1;
    printf("%d\n", u.i != 0);
    return 0;
}