#include using namespace std; constexpr int mod = 1000000007; long long fac[2000005], finv[2000005], inv[2000005]; void COMinit() { fac[0] = fac[1] = finv[0] = finv[1] = inv[1] = 1; for (int i = 2; i < 2000005; i++) { fac[i] = fac[i - 1] * i % mod; inv[i] = mod - inv[mod % i] * (mod / i) % mod; finv[i] = finv[i - 1] * inv[i] % mod; } } long long COM(int n, int k) { if (n-k <= 0) return 1; if (n < k) return 0; if (n < 0 || k < 0) return 0; return fac[n] * (finv[k] * finv[n - k] % mod) % mod; } int main() { int A,B,X,Y; cin >> A >> B >> X >> Y; COMinit(); long long ans = 0; int a = 1+B/4; int b = min(1,B)+(B-1)/4; int c = min(1,B-1)+(B-2)/4; int d = min(1,B-2)+(B-3)/4; if(A-abs(X)-abs(Y) < 0 || (A-abs(X)-abs(Y))%2 != 0) { cout << 0 << endl; return 0; } for(int i = abs(X); i+abs(Y) <= A; i += 2) { int e = (i-abs(X))/2,f = i-e; long long tmp = 1; if(X >= 0) { tmp *= COM(a+f-1,a-1); tmp *= COM(c+e-1,c-1); tmp %= mod; } else { tmp *= COM(c+f-1,c-1); tmp *= COM(a+e-1,a-1); tmp %= mod; } e = ((A-i)-abs(Y))/2,f = (A-i)-e; if(Y >= 0) { tmp *= COM(b+f-1,b-1); tmp %= mod; tmp *= COM(d+e-1,d-1); tmp %= mod; } else { tmp *= COM(d+f-1,d-1); tmp %= mod; tmp *= COM(b+e-1,b-1); tmp %= mod; } ans += tmp; ans %= mod; } cout << ans << endl; }