how bout this one?

  int chare;
  char* s = (char *)malloc(512000 * sizeof(char));
  int count=0;
  gets(s);
  for(int i=0;i<strlen(s);i++)
  s[i]=tolower(s[i]);
  for(chare = 97;chare<=123;chare++)
  {
     for(int i=0;i<strlen(s);i++){
         if(s[i]==(char)chare){
             count++;
             break;
        }
   }
  }
  if(count>=26)
  printf("pangram\n");
  else
  printf("not pangram\n")   ;