Code

#include <iostream>
#include <cstring>
using namespace std;

const int N = 25;
int n, m, x, y;
int f[N][N];

int main() {
    cin >> n >> m >> x >> y;
    f[0][0] = 1;
    for (int i = 0; i <= n; i++) {
        for (int j = 0; j <= m; j++) {
            if (i == x && j == y) {
                continue;
            }
            if (i >= 2 && j >= 1) {
                f[i][j] += f[i - 2][j - 1];
            }
            if (i >= 1 && j >= 2) {
                f[i][j] += f[i - 1][j - 2];
            }
        }
    }
    cout << f[n][m] << endl;
    return 0;
}