n, s, k = map(int, input().split())
mod = 10 **9 +7


def div_num(n, k):
    dp = (n+1) * [1]
    for i in range(2, k+1):
        for j in range(i, n+1):
            dp[j] = dp[j] + dp[j - i] % mod
    return dp[-1]


if s - n *((n-1) * k) //2 < 0:
     print(0)
else:
    print(div_num(s - n *(n-1) * k // 2, n))