from functools import lru_cache
@lru_cache(maxsize=200000)
def f(x, y):
    if x == 0:
        return 1
    if y == 1:
        return 1
    ret = 0
    for i in range(x // y + 1):
        ret += f(x - i * y, y - 1)
        ret %= MOD
    return ret

MOD = 10 ** 9 + 7
N, S, K = map(int, input().split())
S -= K * (N - 1) * N // 2
if S < 0:
    print(0)
    exit()

print(f(S, N))