struct A {long a1; long a2; long a3;} a={1,2,3};
struct B {long a1; long a2; long a3;} b={10,20,30};
struct C {long a1; long a2; long a3;} c={100,200,300};
struct S {long a1; long a2; long a3;} s={(long*)&a,(long*)&b,(long*)&c};
extern long f(long*);

return  ( 111==f((long*)&s));