#include<stdio.h>
#include<stdlib.h>

char *reverse(char *s)
{
	char *p=s,*q=s;	
	while(*q!='\0')
	{
		q++;
	}
	q--;	
	while(q>p)
	{
		char t;
		t=*p;
		*p++=*q;
		*q--=t;		
	}	
	return s;	
}
int main()
{
   char str[7]="HELLO!";
   printf("%s",reverse(str));
	return 0;
}