/in/foo.cc: In function 'int main()':
/in/foo.cc:98:17: warning: unused variable 'x' [-Wunused-variable]
             int x = pre[i].x + dx[j],y = pre[i].y + dy[j];
                 ^
/in/foo.cc:98:38: warning: unused variable 'y' [-Wunused-variable]
             int x = pre[i].x + dx[j],y = pre[i].y + dy[j];
                                      ^