import java.util.*;

public class Main {
  public static void main(String[] args) {
    long MOD = (long)Math.pow(10, 9) + 7;
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    int S = sc.nextInt();
    int K = sc.nextInt();
    // dp[i][j]はi人募金した時点で確定金額がj円となる場合の数
    long[][] dp = new long[N + 1][S + 1];
    dp[0][0] = 1;
    for(int i = 1; i < N + 1; i++) {
      for(int j = 0; j < S + 1; j++) {
        if(j >= K * (N - i + 1)) dp[i][j] = (dp[i][j] + dp[i - 1][j - K * (N - i + 1)]) % MOD;
        if(j >= (N - i + 1)) dp[i][j] = (dp[i][j] + dp[i][j - (N - i + 1)]) % MOD;
      }
    }
    System.out.println(dp[N][S]);
  }
}