typedef struct _aa
{
    int a;
} aa;

typedef struct _bb
{
    int b;
} bb;

typedef struct _cc
{
    aa;
    bb;
    int c;
} cc;

int main(void)
{
    cc c;
    c.a = 20;
    c.b = 40;
    c.c = 30;

    printf("%d", c.b);
    return 0;
}