#include <iostream>
#include <stdio.h>
#include <string.h>
#include <queue>
using namespace std;
#define MAXX 
#define MAXY
struct Node{
    int x,y;
    int step;
};
int n,m;    //边界
int dx[4] = {0,1,0,-1};
int dy[4] = {1,0,-1,0};
int a[MAXX][MAXY];
int isv[MAXX][MAXY];
void judge(int x,int y)
{
    if(x<1 || x>n || y<1 || y>m)
        return true;
    if(isv[x][y])
        return true;
}
void bfs()
{
    memset(isw,0,sizeof(isw));
    queue <int> q;
    int cur,next;
    cur.step = 0;
    isv[cur.x][cur.y] = true;
    q.push(cur);
    while(!q.empty()){
        cur = q.front();
        q.pop();
        int i;
        for(i=1;i<4;i++){
        }
    }
}