/in/foo.c: In function 'main':
/in/foo.c:9:12: warning: unknown conversion type character 0xa in format [-Wformat=]
  printf("d%\n",sum);
            ^
/in/foo.c:9:9: warning: too many arguments for format [-Wformat-extra-args]
  printf("d%\n",sum);
         ^~~~~~
/in/foo.c:6:2: warning: 'n' is used uninitialized in this function [-Wuninitialized]
  for(int i=1;i<=n;i++)
  ^~~