求助！

// luogu-judger-enable-o2
#include<bits/stdc++.h>
using namespace std;
int ans[1001][1001];
int ax[1001][1001],n,m;
int dx[8]= {2,-2,2,-2,-1,1,-1,1};
int dy[8]= {1,1,-1,-1,2,2,-2,-2};
int head,tail,x,y;
struct px {
	int x;
	int y;
	int step;
} a[10001];
void bfs(int stax,int stay) {
	head=0;
	tail=1;
	a[1].x=stax;
	a[1].y=stay;
	a[1].step=1;
	while(head<=tail) {
		++head;
		x=a[head].x;
		y=a[head].y;
		for(int i=0; i<8; i++) {
			int nx=x+dx[i];
			int ny=y+dy[i];
			if(nx>=1&&nx<=n&&ny>=1&&ny<=m) {
				if(ax[nx][ny]==0) {
					ax[nx][ny]=1;
					++tail;
					a[tail].x=nx;
					a[tail].y=ny;
					a[tail].step=a[head].step+1;
					ans[nx][ny]=a[tail].step-1;
				}
			}
		}
	}
}
int main() {
	int a1,b1,l=-1,l1=0;
	cin>>n>>m>>a1>>b1;
	bfs(a1,b1);
	for(int i=1; i<=n; i++) {
		for(int j=1; j<=m; j++) {
			if(i==a1&&j==b1) 
				printf("%-5d",l1);
			else if(((n==1||m==1)||(n==2||m==2))&&((i==a1+1&&j==b1)||(i==a1-1&&j==b1)||(i==a1&&j==b1+1)||(i==a1&&j==b1-1)))
			printf("%-5d",l);
			else if(ans[i][j]==0)
			printf("%-5d",l);
			else
				printf("%-5d",ans[i][j]);
		}
		cout<<endl;
	}
	return 0;
}