/in/foo.cc: In function 'int main()':
/in/foo.cc:7:6: warning: unused variable 'a' [-Wunused-variable]
  int a,k,x;
      ^
/in/foo.cc:11:3: warning: 'k' is used uninitialized in this function [-Wuninitialized]
  k++;
  ~^~