按照一些大佬的满分代码调了很久，还是不对

#include <cstdio>
#include <cstring>
#include <algorithm>
#define INPUT_DATA_TYPE int
#define OUTPUT_DATA_TYPE int

#define QUEUE_DATA_TYPE int
const int QUEUE_SIZE = 50100;
struct QUEUE{
	QUEUE_DATA_TYPE q[QUEUE_SIZE];
	int head,tail,num;

	QUEUE(){
		head=0;
		tail=-1;
		num=0;
		return;
	}

	void push(QUEUE_DATA_TYPE in){
		tail=(tail+1)%QUEUE_SIZE;
		q[tail]=in;
		++num;
		return;
	}

	void pop(){
		head=(head+1)%QUEUE_SIZE;
		--num;
		return;
	}

	void pop_back(){
		tail=(tail-1+QUEUE_SIZE)%QUEUE_SIZE;
		--num;
		return;
	}

	QUEUE_DATA_TYPE front(){
		return q[head];
	}

	QUEUE_DATA_TYPE back(){
		return q[tail];
	}

	void clear(){
		head=0;
		tail=-1;
		num=0;
		return;
	}

	bool empty(){
		if(num==0)
			return true;
		else
			return false;
	}

	int size(){
		return num;
	}

	QUEUE_DATA_TYPE read(int in){
		return q[(head+in)%QUEUE_SIZE];
	}
}Q;

struct node{
    int to,next;
    node(){
        next=-1;
    }
}e[5000005];

int head[50005],d[50005],time[50005],tot;

INPUT_DATA_TYPE read();
void print(OUTPUT_DATA_TYPE x);
void addEdge(int u,int v){
    e[tot].next=head[u];
    e[tot].to=v;
    head[u]=tot;
    ++tot;
}
/*
5 5 2
1 2
4
3 2 1 2
4 3 1 2 3
5 3 1 3 4
1 0
*/
int main(){
    memset(head,-1,sizeof(head));
    memset(time,-1,sizeof(time));
    register int i,j;
    int v,s,u;
    int n=read();
    int k=read();
    int p=read();

    for(i=0;i<p;++i){
        u=read();
        time[u]=0;
        Q.push(u);
    }

    int r=read();

    for(i=1;i<=r;++i){
        v=read();
        s=read();
        d[v]=s;
        for(j=0;j<s;++j){
            u=read();
            addEdge(u,v);
        }
        if(!time[v]) d[v]=0;
    }

    while(!Q.empty()){
        u=Q.front();
        Q.pop();
        for(i=head[u];~i;i=e[i].next){
            --d[e[i].to];
            time[e[i].to]=std::max(time[e[i].to],time[u]+1);
            if(!d[e[i].to]){
                Q.push(e[i].to);
            }
        }
    }

    if(d[k]) time[k]=-1;
    printf("%d",time[k]);

    return 0;
}

INPUT_DATA_TYPE read(){
    register INPUT_DATA_TYPE x=0;register char f=0,c=getchar();
    while(c<'0'||'9'<c)f=(c=='-'),c=getchar();//?=if,:=else
    while('0'<=c&&c<='9')x=(x<<3)+(x<<1)+(c&15),c=getchar();
    return f?-x:x;
}

void print(OUTPUT_DATA_TYPE x){
    register char s[20];
    register int i=0;
    if(x<0){
        x=-x;
        putchar('-');
    }
    if(x==0){
        putchar('0');
        return;
    }
    while(x){
        s[i++]=x%10;
        x/=10;
    }
    while(i){
        putchar(s[--i]+'0');
    }
    return;
}