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

dp = [[0 for _ in range(S+1)] for _ in range(N+1)]
dp[0][0] = 1
dp[1][0] = 1
for i in range(N):
    for j in range(S+1):
        now = j + K * (N-i)
        while(True):
            if(now > S):break
            dp[i+1][now] += dp[i][j]
            dp[i+1][now] %= MOD
            now += N-i

print(dp[-1][S])