/in/foo.cc: In function 'int main()':
/in/foo.cc:12:17: warning: unused variable 'a' [-Wunused-variable]
   12 |         int n,k,a[105];
      |                 ^
/in/foo.cc: In function 'bool _is_xor(int)':
/in/foo.cc:6:23: warning: '__xor' is used uninitialized [-Wuninitialized]
    6 |         return __xor==k;
      |                       ^
/in/foo.cc:5:13: note: '__xor' was declared here
    5 |         int __xor;
      |             ^~~~~