Because it doesn't compile.
if (n<0 || n>MAX)
{
printf("Invalid numbers!");
}```
"`" is not a valid character in C code, so the compiler doesn't like the final line of that code fragment.
If code doesn't compile, then no .EXE file is produced, so the chances are that the app you run doesn't include all that code - just the last successful compilation which didn't include the back-ticks.
Try removing them, and see if it compiles. If it does, see what happens when you run it this time. If it still doesn't do what you expect, use the debugger to find out exactly what it is doing while it runs.