/in/foo.cc: In function 'void dfs2(int)':
/in/foo.cc:74:13: warning: unused variable 'tw' [-Wunused-variable]
         int tw = edq[i].w;
             ^~
/in/foo.cc: In function 'int prim(int)':
/in/foo.cc:181:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^
/in/foo.cc: In function 'int solve(int, int, int)':
/in/foo.cc:123:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^