string = input()
n, d, m, s = tuple(map(int, string.split()))

x = [l for l in range(1,d+1)]
m = m * (-1) - 1
z = [p for p in itertools.product(x, repeat=n) if sum(sorted(p)[:m:-1]) == s]
print(len(z) % (10**9+7))