/in/foo.cc: In function 'int main()':
/in/foo.cc:92:10: warning: unused variable 'a' [-Wunused-variable]
  int x,y,a,b,lastans=0;
          ^
/in/foo.cc:92:12: warning: unused variable 'b' [-Wunused-variable]
  int x,y,a,b,lastans=0;
            ^
/in/foo.cc:92:14: warning: unused variable 'lastans' [-Wunused-variable]
  int x,y,a,b,lastans=0;
              ^~~~~~~