/in/foo.cc: In function 'bool bfs()':
/in/foo.cc:6:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 #define fr(i,s,t) for (i=s;i<=t;i++)
                              
/in/foo.cc:37:6:
   fr(i,0,vec[x].size()-1){
      ~~~~~~~~~~~~~~~~~~~     
/in/foo.cc:37:3: note: in expansion of macro 'fr'
   fr(i,0,vec[x].size()-1){
   ^~
/in/foo.cc: In function 'int dfs(int, int)':
/in/foo.cc:51:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (;cur[x]<vec[x].size();cur[x]++){
        ~~~~~~^~~~~~~~~~~~~~
/in/foo.cc:49:6: warning: unused variable 'i' [-Wunused-variable]
  int i,y,num,flow=0,f;
      ^