#include using namespace std; int n, m, cx, cy; int main() { cin >> n >> m >> cx >> cy;

bool blocked[25][25] = {false};
blocked[cx][cy] = true;

int dx[] = {2, 2, -2, -2, 1, 1, -1, -1};
int dy[] = {1, -1, 1, -1, 2, -2, 2, -2};

for (int i = 0; i < 8; ++i) {
    int nx = cx + dx[i];
    int ny = cy + dy[i];
    if (nx >= 0 && nx <= n && ny >= 0 && ny <= m) {
        blocked[nx][ny] = true;
    }
}

long long dp[25][25] = {0};
dp[0][0] = 1;

for (int j = 1; j <= m; ++j) {
    if (!blocked[0][j]) {
        dp[0][j] = dp[0][j-1];
    }
}

for (int i = 1; i <= n; ++i) {
    if (!blocked[i][0]) {
        dp[i][0] = dp[i-1][0];
    }
}

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

cout << dp[n][m] << endl;

return 0; }
//supermonkey 布置的7891978作业（MAN）