#define Y(x) Z(x)
#define X Y
X(1)
X(X(1))
X(X(X(X(X(1)))))
#define A B
#define B A
return A + B;
#undef A
#undef B
#define A B+1
#define A1 B1+1
#define B1 C1+2
#define C1 A1+3
return A1 + B1;