/in/foo.cc: In function 'void spfa()':
/in/foo.cc:42:22: warning: the address of 'visit' will always evaluate as 'true' [-Waddress]
              if(visit)
                      ^
/in/foo.cc:43:37: error: return-statement with a value, in function returning 'void' [-fpermissive]
                {printf("No");return 0;}
                                     ^