/in/foo.cc: In function 'void spfa()':
/in/foo.cc:71:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(i=0;i<adj[u.id].size();i++)
                 ~^~~~~~~~~~~~~~~~~
/in/foo.cc:56:11: warning: unused variable 'j' [-Wunused-variable]
     int i,j,s,p,q,id,ip,mi;
           ^
/in/foo.cc:56:13: warning: unused variable 's' [-Wunused-variable]
     int i,j,s,p,q,id,ip,mi;
             ^
/in/foo.cc:56:15: warning: unused variable 'p' [-Wunused-variable]
     int i,j,s,p,q,id,ip,mi;
               ^
/in/foo.cc:56:17: warning: unused variable 'q' [-Wunused-variable]
     int i,j,s,p,q,id,ip,mi;
                 ^
/in/foo.cc:56:19: warning: unused variable 'id' [-Wunused-variable]
     int i,j,s,p,q,id,ip,mi;
                   ^~
/in/foo.cc: In function 'int min_cost()':
/in/foo.cc:91:11: warning: unused variable 'j' [-Wunused-variable]
     int i,j,s,p,q,ret=0,id,ip,ie;
           ^
/in/foo.cc:91:13: warning: unused variable 's' [-Wunused-variable]
     int i,j,s,p,q,ret=0,id,ip,ie;
             ^
/in/foo.cc:91:15: warning: unused variable 'p' [-Wunused-variable]
     int i,j,s,p,q,ret=0,id,ip,ie;
               ^
/in/foo.cc:91:17: warning: unused variable 'q' [-Wunused-variable]
     int i,j,s,p,q,ret=0,id,ip,ie;
                 ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:111:13: warning: unused variable 's' [-Wunused-variable]
     int i,j,s,p,q,id;
             ^
/in/foo.cc:111:15: warning: unused variable 'p' [-Wunused-variable]
     int i,j,s,p,q,id;
               ^
/in/foo.cc:111:17: warning: unused variable 'q' [-Wunused-variable]
     int i,j,s,p,q,id;
                 ^
/in/foo.cc:111:19: warning: unused variable 'id' [-Wunused-variable]
     int i,j,s,p,q,id;
                   ^~