#include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <vector>

using namespace std;
using ll = long long;

bool st[25][25];
int dp[25][25];
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    memset(st, 0, sizeof(st));

    int n, m, hx, hy;

    cin >> n >> m >> hx >> hy;

    st[hx][hy] = 1;
    if (hx - 2 >= 0) st[hx - 2][hy + 1] = 1;
    if (hx - 2 >= 0 && hy - 1 >= 0) st[hx - 2][hy - 1] = 1;
    if (hx - 1 >= 0) st[hx - 1][hy + 2] = 1;
    if (hx - 1 >= 0 && hy - 2 >= 0) st[hx - 1][hy - 2] = 1;
    if (hy - 2 >= 0) st[hx + 1][hy - 2] = 1;
    st[hx + 1][hy + 2] = 1;
    if (hy - 1 >= 0) st[hx + 2][hy - 1] = 1;
    st[hx + 2][hy + 1] = 1;

    for (int i = 0; i <= n; i++) {
        for (int j = 0; j <= m; j++) {
            if (!st[i][j]) {
                if (i == 0 && j == 0)
                    dp[i][j] = 1;
                else
                    dp[i][j] = dp[i - 1][j] + dp[i][j - 1];
            }
        }
    }

    cout << dp[n][m] << "\n";

    return 0;
}

$RT$