#include <iostream>
#include <cstring>
#include <string>
#include <cmath>
#include <algorithm>
using namespace std;
long long f[22][22];
int dx[10] = { 0,2,1,-1,-2,-2,-1,1,2 };
int dy[10] = { 0,1,2,2,1,-1,-2,-2,-1 };
int main() {
    int a, b, m, n;
    bool flag;
    cin >> m >> n >> a >> b;
    f[0][0] = 1;
    for (int i = 0; i <= m; i++) {
        for (int j = 0; j <= n; j++) {
            flag = 0;
            for (int k = 1; k <= 8; k++)
                if ((a + dx[k] == i) && (b + dy[k] == j)) flag = 1;
            if (flag == 1) continue;
            if (i > 0)f[i][j] += f[i - 1][j];
            if (j > 0)f[i][j] += f[i][j - 1];
        }
    }
    /*for (int i = 0; i <= m; i++) {
        for (int j = 0; j <= n; j++) cout << f[i][j] << ' ';
        cout << endl;
    } */
    cout << f[m][n];
    return 0;
}
//I will AK CSP and IOI