#include <iostream>

using namespace std;

bool flag[101][101] = {false};
int a[101][101];
int bx,by;
int ma,mb;

int main () {
	cin >> by >> bx;
	cin >> ma >> mb;
	
	
	for (int i = 0; i < by; i++) {
		a[i][0] = 1;
	}
	for (int i = 0; i < bx; i++) {
		a[0][i] = 1;
	}
	flag[ma - 1][mb - 2] = true;;
	flag[ma - 1][mb + 2] = true;
	flag[ma + 1][mb - 2] = true;
	flag[ma + 1][mb + 2] = true;
	flag[ma - 2][mb - 1] = true;
	flag[ma - 2][mb + 1] = true;
	flag[ma + 2][mb - 1] = true;
	flag[ma + 2][mb + 1] = true;
	
	for (int i = 1; i < by + 1; i++) {
		for (int j = 1; j < bx + 1; j++) {
			if (flag[i][j] != true) {
				a[i][j] = a[i][j - 1] + a[i - 1][j];
			}
			else {
				a[i][j] = 0;
			}
		}
	}
	cout << a[by][bx];
	
	return 0;
}