/in/foo.cc: In function 'void Init()':
/in/foo.cc:71:6: warning: unused variable '_2' [-Wunused-variable]
  int _2=0;
      ^~
/in/foo.cc: In function 'int main()':
/in/foo.cc:89:10: warning: unused variable 'a' [-Wunused-variable]
  int x,y,a,b,lastans=0;
          ^
/in/foo.cc:89:12: warning: unused variable 'b' [-Wunused-variable]
  int x,y,a,b,lastans=0;
            ^
/in/foo.cc:89:14: warning: unused variable 'lastans' [-Wunused-variable]
  int x,y,a,b,lastans=0;
              ^~~~~~~