import java.util.*;
import java.io.*;

public class Main {
    static final int MOD = 1000000007;
    public static void main(String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String[] first = br.readLine().split(" ", 3);
        int n = Integer.parseInt(first[0]);
        int s = Integer.parseInt(first[1]);
        int kk = Integer.parseInt(first[2]);
        int total = s - n * (n - 1) / 2 * kk;
       if (total < 0) {
            System.out.println(0);
            return;
        }
        int[][] dp = new int[n + 1][total + 1];
        dp[0][0] = 1;
        for (int i = 1; i < n; i++) {
            for (int j = 0; j <= total; j++) {
                if (dp[i - 1][j] == 0) {
                    continue;
                }
                for (int k = 0; k * (n - i + 1) + j <= total; k++) {
                    int value = k * (n - i + 1) + j;
                    dp[i][value] += dp[i - 1][j];
                    dp[i][value] %= MOD;
                }
            }
        }
        int sum = 0;
        for (int i = 0; i <= total; i++ ) {
            sum += dp[n - 1][i];
            sum %= MOD;
        }
        System.out.println(sum);
    }
}