/in/foo.cc: In function 'int tarjan(int, int)':
/in/foo.cc:36:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:76:32: warning: 'k' may be used uninitialized in this function [-Wmaybe-uninitialized]
     last[e.y][++last[e.y][0]]=k;
                                ^