What would be the difference between following macro definition?

Question

1)

#define begin main

void begin() {

}

2)

#define begin  m # # a # # i # # n

void begin() {

}

3)

#define(m,a,i,n) m # # a # # i # # n

# define start begin(m,a,i,n)

void start()
{

}