import sys

sys.setrecursionlimit(10 ** 6)
def MI(): return map(int, sys.stdin.readline().split())

md = 10 ** 9 + 7
def main():
    # n人でx円払う方法
    memo = {}

    def p(n, x):
        if x<0:return 0
        if n == 1: return 1
        if (n, x) in memo: return memo[n, x]
        res = p(n - 1, x)
        if x - n >= 0: res += p(n, x - n)
        res %= md
        memo[n, x] = res
        return res

    n, s, k = MI()
    print(p(n, s - k * n * (n - 1) // 2))

main()