/in/foo.cc:7:22: warning: integer overflow in expression [-Woverflow]
 const int mod=(1<<31)-1;
               ~~~~~~~^~
/in/foo.cc: In function 'void dj()':
/in/foo.cc:28:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(ri i=0;i<to[now].size();i++){
              ~^~~~~~~~~~~~~~~