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):
        for k in range(K,10**18):
            if(j+k*(N-i) > S):break
            dp[i+1][j+k*(N-i)] += dp[i][j]
            dp[i+1][j+k*(N-i)] %= MOD

print(dp[-1][S])