//use proconio::input!;
//--------------------------------------------------------
macro_rules! input {
	(source = $s:expr, $($r:tt)*) => {
		let mut iter = $s.split_whitespace();
		let mut next = || { iter.next().unwrap() };
		input_inner!{next, $($r)*}
	};
	($($r:tt)*) => {
		let stdin = std::io::stdin();
		let mut bytes = std::io::Read::bytes(std::io::BufReader::new(stdin.lock()));
		let mut next = move || -> String{
			bytes
				.by_ref()
				.map(|r|r.unwrap() as char)
				.skip_while(|c|c.is_whitespace())
				.take_while(|c|!c.is_whitespace())
				.collect()
		};
		input_inner!{next, $($r)*}
	};
}

macro_rules! input_inner {
	($next:expr) => {};
	($next:expr, ) => {};

	($next:expr, $var:ident : $t:tt $($r:tt)*) => {
		let $var = read_value!($next, $t);
		input_inner!{$next $($r)*}
	};
}

macro_rules! read_value {
	($next:expr, ( $($t:tt),* )) => {
		( $(read_value!($next, $t)),* )
	};

	($next:expr, [ $t:tt ; $len:expr ]) => {
		(0..$len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()
	};

	($next:expr, chars) => {
		read_value!($next, String).chars().collect::<Vec<char>>()
	};

	($next:expr, usize1) => {
		read_value!($next, usize) - 1
	};

	($next:expr, $t:ty) => {
		$next().parse::<$t>().expect("Parse error")
	};
}




const MOD: u32 = 1_000_000_007;
fn main()
{
	input!
	{
		n: usize,
		s: usize,
		k: usize
	}

	if s < (n - 1) * n / 2 * k
	{
		println!("{}", 0);
		return;
	}




	let s = s - (n - 1) * n / 2 * k;

	let mut dp = vec![vec![0_u32; s + 1]; n + 1];
	dp[0][0] = 1;
	for i in 1..=n
	{
		for j in 0..=s
		{
			dp[i][j] += dp[i - 1][j];
			dp[i][j] %= MOD;

			if j.checked_sub(i).is_some() { dp[i][j] += dp[i][j - i]; }
			dp[i][j] %= MOD;
		}
	}




	// dbg!(&dp);
	println!("{}", dp[n][s]);
}