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]; for(int i = 0; i < N + 1; i++) { if(N * i < S + 1) dp[0][N * i] = 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]); } }