求助！！

#include<iostream>
#include<algorithm>
#include<queue>
using namespace std;
#define  MAX  500
int s[MAX][MAX] ;
struct point {
	int x, y, t;
};
queue<struct point> G;
int main() {
	int n, m, x, y,t;//n*m矩阵，起始位置（x,y）
	cin >> n >> m >> x >> y;
	struct point A[MAX],B;
	A[0].x = x; A[0].y = y; A[0].t = 0;
	memset(s, -1, sizeof(s));
	s[x][y] = 0;
	G.push(A[0]);
	while (!G.empty()) {
		x = G.front().x; y = G.front().y; t = G.front().t;
		if (x + 1 <= n && y + 2 <= m) {
			B.x = x + 1;	 B.y = y + 2;	B.t = t + 1;
			if (s[B.x][B.y] == -1) {
				s[B.x][B.y] = B.t;		G.push(B);
			}
		}
		if (x + 2 <= n && y + 1 <= m) {
			B.x = x + 2;	 B.y = y + 1;	B.t = t + 1;
			if (s[B.x][B.y] == -1) {
				s[B.x][B.y] = B.t;		G.push(B);
			}
		}
		if (x + 1 <= n && y - 2 > 0) {
			B.x = x + 1;	 B.y = y - 2;	B.t = t + 1;
			if (s[B.x][B.y] == -1) {
				s[B.x][B.y] = B.t;		G.push(B);
			}
		}
		if (x + 2 <= n && y - 1 >0) {
			B.x = x + 2;	 B.y = y - 1;	B.t = t + 1;
			if (s[B.x][B.y] == -1) {
				s[B.x][B.y] = B.t;		G.push(B);
			}
		}
		if (x - 1 > 0 && y + 2 <= m) {
			B.x = x - 1;	 B.y = y + 2;	B.t = t + 1;
			if (s[B.x][B.y] == -1) {
				s[B.x][B.y] = B.t;		G.push(B);
			}
		}
		if (x - 2 > 0 && y + 1 <= m) {
			B.x = x - 2;	 B.y = y + 1;	B.t = t + 1; 
			if (s[B.x][B.y] == -1) {
				s[B.x][B.y] = B.t;		G.push(B);
			}
		}
		if (x - 1 > 0 && y - 2 > 0) {
			B.x = x - 1;	 B.y = y - 2;	B.t = t + 1;	
			if (s[B.x][B.y] == -1) {
				s[B.x][B.y] = B.t;		G.push(B);
			}
				
		}
		if (x - 2 > 0 && y - 1 > 0) {
			B.x = x - 2;	 B.y = y - 1;	 B.t = t + 1;
			if (s[B.x][B.y] == -1) {
				s[B.x][B.y] = B.t;		G.push(B);
			}
		}
		G.pop();
	}
	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= m; j++) {
			cout << s[i][j] ;
		}
		cout<<endl;
	}
	return 0;
}