#include <iostream>
using namespace std;
int n, m, x, y;
int f[100][100];
bool G[100][100];
int main() {
	cin >> n >> m >> x >> y;
	f[0][0] = 1;
	G[x][y] = G[x-2][y-1] = G[x-2][y+1] = G[x-1][y+2] = G[x+1][y+2] = G[x+2][y+1] = G[x+2][y-1]= G[x+1][y-2] = G[x-1][y-2] = 1;
	for (int i = 0; i <= n; i ++) {
		for (int j = 0; j <= m; j ++) {
			if (i == 0 && j == 0) continue;
			if (!G[i][j]) {
				if (i == 0 && j != 0) {
					f[i][j] = f[i][j - 1];
				} else if (j == 0 && i != 0) {
					f[i][j] = f[i - 1][j];
				} else {
					f[i][j] = f[i][j - 1] + f[i - 1][j];
				}
			}
		}
	}
	cout << f[n][m];
	return 0;
}

又WA又RE的