本地测试通过，洛谷评测玄学WA，求助!

#include<cstdio>
#define ll long long
using namespace std;
int n,m,x,y;
int main()
{
    int i,j;
    scanf("%d%d%d%d",&n,&m,&x,&y);
    n++; m++; x++; y++;
    ll a[n+1][m+1],b[n+1][m+1];
    for (i=0;i<=n;i++)
    	for (j=0;j<=n;j++)
    	{
    		a[i][j]=0;
    		b[i][j]=1;
		}
    a[1][1]=1;
    b[x][y]=0;
    if (x>2&&y>1) b[x-2][y-1]=0;
    if (x>2) b[x-2][y+1]=0;
    if (x>1&&y>2) b[x-1][y-2]=0;
    if (x>1) b[x-1][y+2]=0;
    if (y>2) b[x+1][y-2]=0;
    if (y>1) b[x+2][y-1]=0;
    b[x+2][y+1]=0;
    b[x+1][y+2]=0;
    for (i=1;i<=n;i++)
        for (j=1;j<=m;j++)
        {
            a[i][j]=a[i][j]+a[i-1][j]+a[i][j-1];
            if (b[i][j]==0) a[i][j]=0;
        }
    printf("%lld",a[n][m]);
}