class Combination:
    """
    SIZEが10**6程度以下の二項係数を何回も呼び出したいときに使う
    使い方:
    comb = Combination(SIZE, MOD)
    comb(10, 3) => 120
    """

    def __init__(self, N, MOD=10 ** 9 + 7):
        self.MOD = MOD
        self.__make_factorial_list(N)

    def __call__(self, n, k):
        if k < 0 or k > n:
            return 0
        res = self.fact[n] * self.inv[k] % self.MOD
        res = res * self.inv[n - k] % self.MOD
        return res

    def nPk(self, n, k):
        if k < 0 or k > n:
            return 0
        return self.fact[n] * self.inv[n - k] % self.MOD

    def nHk(self, n, k):
        if k == 0:
            return 1
        return self.__call__(n + k - 1, k)

    def __make_factorial_list(self, N):
        self.fact = [1] * (N + 1)
        self.inv = [1] * (N + 1)
        MOD = self.MOD
        for i in range(1, N + 1):
            self.fact[i] = (self.fact[i - 1] * i) % MOD
        self.inv[N] = pow(self.fact[N], MOD - 2, MOD)
        for i in range(N, 0, -1):
            self.inv[i - 1] = (self.inv[i] * i) % MOD
        return


N, M, D1, D2 = map(int, input().split())
mod = 10**9+7
comb = Combination(N+M, mod)

ans = 0
for i in range(N):
    power = D1*(N-1) + i*(D2-D1+1)
    need = M-1-power
    if need < 0:
        continue
    cnt = comb(N-1, i) * comb(need + N, N) % mod
    if i % 2 == 0:
        ans += cnt
    else:
        ans += mod - cnt
    ans %= mod
print(ans)