/in/foo.cc: In function 'int qujian(int, int, int, int, int*)':
/in/foo.cc:27:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:10:8: warning: 'u' is used uninitialized in this function [-Wuninitialized]
  qujian(u,v,q,n,a);
  ~~~~~~^~~~~~~~~~~
/in/foo.cc:10:8: warning: 'v' is used uninitialized in this function [-Wuninitialized]