#include<bits/stdc++.h>
#define int long long
using namespace std;
long long xx[8]={2,2,1,1,-1,-1,-2,-2};
long long yy[8]={1,-1,2,-2,2,-2,1,-1};
long long a[23][23];
signed main()
{
	long long n,m,x,y;
	cin>>n>>m>>x>>y;
	for (int i = 0; i <= n; i++)
	{
		for (int j = 0; j <= m; j++)
		{
			a[i][j]=1;
		}
	}
	a[x][y]=0;
	for (int i=0; i<8;i++)
	{
		if (xx[i]+x < 0 || yy[i]+y < 0 || xx[i]+x > n || yy[i]+y > m)
		{
			continue;
		}
		a[xx[i]+x][yy[i]+y]=0;
	}
	for (int i = 1; i <= n; i++)
	{
		for (int j = 1; j <= m; j++)
		{
			if (a[i][j] == 0) continue;
			if (a[i][j] == 1) a[i][j]=a[i-1][j]+a[i][j-1];
		}
	}
	cout << a[n][m] << endl;
	return 0;
}

3、4点不对 求助