/in/foo.cc: In function 'int main()':
/in/foo.cc:29:5: warning: unused variable 'n' [-Wunused-variable]
 int n;
     ^
/in/foo.cc:30:6: warning: unused variable 'b' [-Wunused-variable]
  int b[100];
      ^
/in/foo.cc:31:6: warning: unused variable 'x' [-Wunused-variable]
  int x;
      ^