/in/foo.cc: In function 'void dfs(int, int)':
/in/foo.cc:21:8: warning: unused variable 'j' [-Wunused-variable]
  int i,j,x1,y1;
        ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:56:10: warning: variable 'x' set but not used [-Wunused-but-set-variable]
  int i,j,x,y;
          ^
/in/foo.cc:56:12: warning: variable 'y' set but not used [-Wunused-but-set-variable]
  int i,j,x,y;
            ^