#include<stdio.h>
#include<stdlib.h>
#include<math.h>
#define r 15/2
typedef int Vertex;
typedef int WeightType;
typedef struct GNode* MGraph;
int queue[2502] = {-1};
int dist[2502] = {-1};
int path[2502] = {-1};
struct GNode {
    Vertex x, y;
};
int coordienum, jumpdist;
void Save007(MGraph Graph);
int Unweighted(MGraph S);
int IsSafe(MGraph human, int i);
int FirstJump(struct GNode Graph);
int Jump(struct GNode Graph1, struct GNode Graph2);
MGraph CreateCoordieLoacation();
int main()
{
    //创建湖泊和鳄鱼的位置
    //分析如何去岸边
    for (int i = 0; i < 2502; i++)
    {
        path[i] = -1;
        dist[i] = -1;
    }
    MGraph Graph = NULL;
    Save007(Graph);
    while (1);
}

void Save007(MGraph Graph)    //拯救的过程
{
    int judge;
    Graph = CreateCoordieLoacation();
    judge=Unweighted(Graph);
    if (judge != 0)
    {
        dist[judge] += 3;
        printf("%d\n", dist[judge]);
        while (path[judge] != judge)
        {
            printf("%d %d\n", Graph[judge].x, Graph[judge].y);
            judge = path[judge];
        }
        printf("%d %d\n", Graph[judge].x, Graph[judge].y);
    }
    else {
        printf("0\n");
    }
}

int Unweighted(MGraph S)    //找到最短路径
{
    int tail=-1, front=-1;
    int V,answer=0;
    for (int i = 0; i < coordienum; i++)
    {
        if (FirstJump(S[i]))
        {
            queue[++tail] = i;
        }
    }
    while (front < tail)
    {
        
        V = queue[++front]; if (IsSafe(S, V)) return V;
        else
            for (int i = 0; i < coordienum; i++)
            {
                if(Jump(S[V],S[i]))
                    if (dist[i] == -1) {
                        dist[i] = dist[V] + 1;
                        path[i] = V;
                        queue[++tail] = i;
                    }
            }
    }
    return 0;
}

int IsSafe(MGraph human, int i)    //是否获救
{
    if (50-abs(human[i].x) <= jumpdist || 50-abs(human[i].y) <= jumpdist)
        return 1;
    return 0;
}

int FirstJump(struct GNode Graph)    //第一跳
{
    if (sqrt(pow(Graph.x, 2) + pow(Graph.y, 2)) < jumpdist + r)
        return 1;
    return 0;
}

int Jump(struct GNode Graph1, struct GNode Graph2)    //判断是否可以跳,也就是判断是否为临节点
{
    if (sqrt(pow(Graph1.x - Graph2.x, 2) + pow(Graph1.y - Graph2.y, 2)) < jumpdist)
        return 1;
    return 0;
}

MGraph CreateCoordieLoacation()
{
    scanf_s("%d%d", &coordienum, &jumpdist);
    MGraph Graph = (MGraph)malloc(sizeof(struct GNode)*coordienum);
    for (int i = 0; i < coordienum; i++)
    {
        scanf_s("%d%d", &Graph[i].x, &Graph[i].y);
    }
    return Graph;
}

注：放在PTA上不会对哦，因为我没有用堆栈输出，所以会造成与PTA题目上相反的答案，所以你们需要制作一个堆栈在来输出