https://www.luogu.org/problemnew/show/P1002

/*
*@Author:   STZG
*@Language: C++
*/
#include <bits/stdc++.h>
#include<iostream>
#include<algorithm>
#include<cstdlib>
#include<cstring>
#include<cstdio>
#include<string>
#include<vector>
#include<bitset>
#include<queue>
#include<deque>
#include<stack>
#include<cmath>
#include<list>
#include<map>
#include<set>
//#define DEBUG

using namespace std;
typedef long long ll;
const int N=10000;
const double PI = acos(-1.0);
const double EXP = 1E-8;
const int INF = 0x3f3f3f3f;
int t,n,m;

int main()
{
#ifdef DEBUG
	freopen("input.in", "r", stdin);
	//freopen("output.out", "w", stdout);
#endif

	ll n,m,x,y,a[21][21],bx,by,b[21][21];
	int dx[]={2,2,1,-1,-2,-2,-1,1};
	int dy[]={-1,1,2,2,1,-1,-2,-2};
	while(scanf("%lld%lld%lld%lld",&n,&m,&x,&y)!=EOF)
	{
		memset(a,0,sizeof(a));
		memset(b,0,sizeof(b));
		for(int i=0;i<8;i++)
		{
			bx=x+dx[i];
			by=y+dy[i];
			if(bx>=0&&by>=0&&bx<=20&&by<=20)
			b[bx][by]=1;
		}
		b[x][y]=1;
	for(int i=0;i<=n;i++)
	{
		for(int j=0;j<=m;j++)
		{
			if(b[i][j]) continue;
			ll cnt=0;
			if(i>=1 && !b[i-1][j]) cnt+=a[i-1][j];
			if(j>=1 && !b[i][j-1]) cnt+=a[i][j-1];
			a[i][j]=cnt;
			 if(i==0 && j==0) a[0][0]=1;
			// printf("%lld",a[i][j]);
		}
		//printf("\n");
	}

		printf("%lld\n",a[n][m]);
	}

    //cout << "Hello world!" << endl;
    return 0;
}