/in/foo.cc: In function 'int swp(int*, int*)':
/in/foo.cc:25:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^
/in/foo.cc: In function 'void spfa(int)':
/in/foo.cc:52:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int i=0;i<map[T].size();i++)
                     ~^~~~~~~~~~~~~~