/in/foo.cc: In function 'int bfs(int, int)':
/in/foo.cc:27:16: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
     if(tx[head]=ttx&&ty[head]!=tty)
        ~~~~~~~~^~~~~~~~~~~~~~~~~~~
/in/foo.cc:29:16: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
     if(ty[head]=tty&&tx[head]!=ttx)
        ~~~~~~~~^~~~~~~~~~~~~~~~~~~
/in/foo.cc:53:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^