Two fun C-language programs

My classmate test me a question.

1. Write a C language program, output Hello, delete the first character of the Code, output world.

2. Write a C language program, output Hello, delete the last character of the Code, output world.

Thought for a while, wrote the two code, haha, again worship the C language grammar.

Time

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*
#define CQSB
//*/
#include <stdio.h>
int main ()
{
    int a=0;
    #ifdef CQSB
    puts ("Hello");
    a=1;
    #endif
    if (!a) puts ("World");
    return 0;
}

#include <stdio.h>
#define PP Main () {puts ("Hello");}
#define P Main () {puts ("World");}
Pp