/* 
 *     Author:  srtry
 *     Created: 2025-10-12T09:51:49+09:00
 *     Coding:  utf-8-unix
 */

use proconio::input;
use std::io::{stdout,Write,BufWriter};

const big:usize = 1000000007;
const n_max:usize = 100;
const s_max:usize = 20000;
const k_max:usize = 100;

fn main() {
    input!{
        n:usize, s:usize, k:usize
    }

    let out = stdout();
    let mut out = BufWriter::new(out.lock());
    
    let mut ans:usize = 0;

    let mut dp:[usize;s_max+1] = [0;s_max+1];
    dp[0] = 1;
    let b:usize = if k*(n-1)*n/2 > s {
        write!(out, "0").unwrap();
        return
    } else {
        s - k*(n-1)*n/2 
    };
    
    for i in 1..=n {
        for j in i..=b {
            dp[j] = (dp[j] + dp[j-i])%big;
        }
    }

    write!(out, "{}", dp[b]).unwrap();
}