import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Deque;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.PriorityQueue;
import java.util.Queue;
import java.util.Scanner;
 
 
public class Main {


	public static void main(String[] args) {
		// TODO Auto-generated method stub
		//int Q = Integer.parseInt(sc.next());
		//long L = Long.parseLong(sc.next());
		//char[] c = sc.next().toCharArray();
		int INF = Integer.MAX_VALUE;
		Scanner sc = new Scanner(System.in);
		
		int N = Integer.parseInt(sc.next());
		int S = Integer.parseInt(sc.next());
		int K = Integer.parseInt(sc.next());
		int MOD = 1_000_000_007;
		
		int M = S - N*(N-1)*K/2;
		if(M<0){	//見栄張りすぎ
			System.out.println("0");
			return;
		}
		
		//MのN分割を求める
		int[][] dp = new int[N+1][M+1];
		dp[0][0] = 1;
		for(int i=1;i<=N;i++){
			for(int j=0; j<=M; j++){
				
				if(j-i>=0){
					dp[i][j] = (dp[i][j-i] + dp[i-1][j])%MOD;
				}else{
					dp[i][j] = dp[i-1][j]%MOD;
				}
				
			}
		}
		
		System.out.println(dp[N][M]);
	}
}