/in/foo.c: In function 'main':
/in/foo.c:8:13: warning: spurious trailing '%' in format [-Wformat=]
  printf("GUN%");
             ^
/in/foo.c:9:11: warning: format '%s' expects argument of type 'char *', but argument 2 has type 'int' [-Wformat=]
  printf("%s",GNU(n));
           ^
/in/foo.c: In function 'GNU':
/in/foo.c:16:2: warning: control reaches end of non-void function [-Wreturn-type]
  }
  ^