#include<bits/stdc++.h>
using namespace std;
unsigned long long n,m,x,y,i,j,b[25][25];
bool a[25][25];
int main(){
    cin >> n >> m >> x >> y;
    a[x][y] = a[x + 2][y + 1] = a[x + 2][y - 1] = a[x - 2][y + 1] = a[x - 2][y - 1] = 1;
	a[x + 1][y + 2] = a[x - 1][y + 2] = a[x + 1][y - 2] = a[x - 1][y - 2] = 1;
    b[0][0] = 1;
    for(i = 1; i <= n; i++){
    	if(a[i][0]) continue;
    	b[i][0] = b[i - 1][0];
    }
    for(i = 1; i <= m; i++){
    	if(a[0][i]) continue;
    	b[0][i] = b[0][i - 1];
    }
    for(i = 1; i <= n; i++){
    	for(j = 1; j <= m; j++){
    		if(a[i][j]) continue;
    		b[i][j] = b[i - 1][j] + b[i][j - 1];
    	}
    }
    cout<< b[n][m] ;
    return 0;
}