n, S, K = map(int, input().split())
MOD = 10**9 + 7

required = K * n * (n - 1) // 2
S_prime = S - required

if S_prime < 0:
    print(0)
else:
    r = S_prime % n
    if S_prime < r:
        print(0)
    else:
        dp = [0] * (S_prime + 1)
        dp[0] = 1
        for j in range(2, n + 1):
            c_j = n - j + 1
            for v in range(c_j, S_prime + 1):
                dp[v] = (dp[v] + dp[v - c_j]) % MOD
        
        total = 0
        t = r
        while t <= S_prime:
            total = (total + dp[t]) % MOD
            t += n
        print(total % MOD)