#include <stdio.h>
char *no_space(char *);
 
int main(void) {
 
  char strin[] = "HELLO WORLD";
 
  printf("%s\n", strin);
  printf("%s\n", no_space(strin));
 
  return 0;
}
 
char *no_space(char *strin){
 
 int i = 0, c = 0;
   
    for ( ; strin [i] ; i++ ){
     
     if ( strin[i] != ' ' )
       
        strin[c++] = strin[i];
 
    }
   
  strin[c]= '\0';
 
 return strin;
}