/in/foo.cc: In function 'void add(int, int, int)':
/in/foo.cc:10:1: error: 'xu' was not declared in this scope
 xu[++tot].x=x;xu[tot].y=y;xu[tot].w=w;xu[tot].nxt=head[x];head[x]=tot;
 ^~
/in/foo.cc: In function 'void SPFA(int)':
/in/foo.cc:19:25: error: 'xu' was not declared in this scope
   for(int i=head[u];i;i=xu[i].nxt){
                         ^~
/in/foo.cc:21:21: error: 'w' was not declared in this scope
    if(dis[v]>dis[u]+w){
                     ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:32:24: error: 'a' was not declared in this scope
  while(scanf("%d%d%d",&a,&b,&r)==3 && a!=0) add(a,b,r);
                        ^
/in/foo.cc:32:27: error: 'b' was not declared in this scope
  while(scanf("%d%d%d",&a,&b,&r)==3 && a!=0) add(a,b,r);
                           ^
/in/foo.cc:32:30: error: 'r' was not declared in this scope
  while(scanf("%d%d%d",&a,&b,&r)==3 && a!=0) add(a,b,r);
                              ^