/in/foo.cc: In function 'int main()':
/in/foo.cc:45:15: warning: 'y' may be used uninitialized in this function [-Wmaybe-uninitialized]
     DFS(0,x,y);
               ^
/in/foo.cc:45:15: warning: 'x' may be used uninitialized in this function [-Wmaybe-uninitialized]