#include<iostream>
#include<cstdlib>
#include<cstdio>
#include<cmath>
#include<bits/stdc++.h>
using namespace std;

int b[900]; 
long long f[100][100];
int hx[] = {0, -2, -1, 1, 2, 2, 1, -1, -2};
int hy[] = {0, 1, 2, 2, 1, -1, -2, -2, -1};
int s[20][20];

int main(){
	
	int n, m, x, y;
	cin >> n >> m >> x >> y; 
	f[2][1] = 1;
	for(int i = 1; i <= 8; i++){
		s[x + hx[i]][y + hy[i]] = 1;
	}
	for(int i = 2; i <= n; i++){
		for(int j = 2; j <= m; j++){
			if(s[i][j]){
				continue;
			}
			f[i][j] = f[i - 1][j] + f[i][j - 1];
		}
	}
	cout << f[n][m] << endl;
    return 0;
}