N, S, K = gets.split.map(&:to_i)
MOD = 10 ** 9 + 7

dp = Array.new(N + 1) { Array.new(S + 1, 0) }

0.step(S, N) do |s|
  dp[0][s] = 1
end

1.upto(N - 1) do |i|
  0.upto(S) do |s|
    m = N - i

    if s >= K * m
      dp[i][s] += dp[i - 1][s - K * m]
    end

    if s - m >= 0
      dp[i][s] += dp[i][s - m]
    end

    dp[i][s] %= MOD
  end
end

puts dp[N - 1][S]