#include <bits/stdc++.h>
using namespace std;

int main() {
  int n, m; cin >> n >> m;
  unsigned long long res[m+1][n+1];
  for(int i = 0; i <= m; i++) memset(res[i], 0, sizeof(res[i]));
  int kn, km; cin >> kn >> km;

  for(int i = 0; i <= m; i++) {
    for(int j = 0; j <= n; j++) {
      if(i * j == 0) res[i][j] = 1;
      else res[i][j] = res[i-1][j] + res[i][j-1];
      if(
         (i == km && j == kn)
         || abs(i-km) * abs(j-kn) == 2
	) res[i][j] = 0;
    }
  }
  cout << res[m][n] << endl;
}

哪位大佬看看这哪里错了啊啊啊