P = 10**9 + 7
N, S, K = map(int, raw_input().split())
dp = [[0] * (S+1) for i in xrange(N)]
for i in xrange(0, S+1, N):
    dp[0][i] = 1
for i in xrange(1, N):
    for j in xrange(0, S+1):
        if j-K*(N-i) >= 0:
            dp[i][j] += dp[i-1][j-K*(N-i)]
        if j-(N-i) >= 0:
            dp[i][j] += dp[i][j-(N-i)]
        dp[i][j] %= P
print(dp[N-1][S])