#include<iostream>
#include<algorithm>

using namespace std;

long long  m,n,hx,hy;
const int N = 30;
long long cnt=0;
int a[N][N];
void dfs(int x,int y)//xy代表现在的位置 
{
	if(x>n||y>m) return ;
	if(x==n&&y==m)
	{
		cnt++;
		return ;
	}
	//向右走 
	if(a[x][y+1]==0){
		a[x][y+1]=1;
		dfs(x,y+1);
		a[x][y+1]=0;
	}
	//向下走 
	if(a[x+1][y]==0){
		a[x+1][y]=1;
		dfs(x+1,y);
		a[x+1][y]=0;
	}
}

int main ()
{

	cin >> m >> n >> hx >> hy;
	a[hx][hy]=2;
	a[hx+2][hy+1]=2;a[hx+1][hy+2]=2;a[hx-1][hy+2]=2;a[hx-2][hy+1]=2;
	a[hx-2][hy-1]=2;a[hx-1][hy-2]=2;a[hx+1][hy-2]=2;a[hx+2][hy-1]=2;
	dfs(0,0);
	cout << cnt;
	return 0;
}
`````