package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

func configure(scanner *bufio.Scanner) {
	scanner.Split(bufio.ScanWords)
	scanner.Buffer(make([]byte, 1000005), 1000005)
}
func getNextString(scanner *bufio.Scanner) string {
	scanned := scanner.Scan()
	if !scanned {
		panic("scan failed")
	}
	return scanner.Text()
}
func getNextInt(scanner *bufio.Scanner) int {
	i, _ := strconv.Atoi(getNextString(scanner))
	return i
}
func getNextInt64(scanner *bufio.Scanner) int64 {
	i, _ := strconv.ParseInt(getNextString(scanner), 10, 64)
	return i
}
func getNextFloat64(scanner *bufio.Scanner) float64 {
	i, _ := strconv.ParseFloat(getNextString(scanner), 64)
	return i
}
func main() {
	fp := os.Stdin
	wfp := os.Stdout
	extra := 0
	if os.Getenv("I") == "IronMan" {
		fp, _ = os.Open(os.Getenv("END_GAME"))
		extra = 100
	}
	scanner := bufio.NewScanner(fp)
	configure(scanner)
	writer := bufio.NewWriter(wfp)
	defer func() {
		r := recover()
		if r != nil {
			fmt.Fprintln(writer, r)
		}
		writer.Flush()
	}()
	solve(scanner, writer)
	for i := 0; i < extra; i++ {
		fmt.Fprintln(writer, "-----------------------------------")
		solve(scanner, writer)
	}
}
func solve(scanner *bufio.Scanner, writer *bufio.Writer) {
	n := getNextInt(scanner)
	s := getNextInt(scanner)
	k := getNextInt(scanner)
	s -= (n - 1) * n * k / 2
	if s < 0 {
		fmt.Fprintln(writer, 0)
		return
	}
	if s == 0 {
		fmt.Fprintln(writer, 1)
		return
	}
	dp := makeGrid(n+1, s+1)
	dp[1][1] = 1
	for i := 1; i < n+1; i++ {
		for j := 1; j < s; j++ {
			if i < n {
				dp[i+1][j+1].AddAs(dp[i][j])
			}
			if i+j < s+1 {
				dp[i][i+j].AddAs(dp[i][j])
			}
		}
	}
	var ans Mint
	for i := 0; i < n+1; i++ {
		ans.AddAs(dp[i][s])
	}
	fmt.Fprintln(writer, ans)
}
func makeGrid(h, w int) [][]Mint {
	index := make([][]Mint, h, h)
	data := make([]Mint, h*w, h*w)
	for i := 0; i < h; i++ {
		index[i] = data[i*w : (i+1)*w]
	}
	return index
}

// Mod constants.
const (
	Mod1000000007 = 1000000007
	Mod998244353  = 998244353
)

var mod Mint = Mod1000000007

// Mint treats the modular arithmetic
type Mint int64

// SetMod sets the mod. It must be called first.
func SetMod(newmod Mint) {
	mod = newmod
}

// Mod returns m % mod.
func (m Mint) Mod() Mint {
	m %= mod
	if m < 0 {
		return m + mod
	}
	return m
}

// Inv returns modular multiplicative inverse
func (m Mint) Inv() Mint {
	return m.Pow(Mint(0).Sub(2))
}

// Pow returns m^n
func (m Mint) Pow(n Mint) Mint {
	p := Mint(1)
	for n > 0 {
		if n&1 == 1 {
			p.MulAs(m)
		}
		m.MulAs(m)
		n >>= 1
	}
	return p
}

// Add returns m+x
func (m Mint) Add(x Mint) Mint {
	return (m + x).Mod()
}

// Sub returns m-x
func (m Mint) Sub(x Mint) Mint {
	return (m - x).Mod()
}

// Mul returns m*x
func (m Mint) Mul(x Mint) Mint {
	return (m * x).Mod()
}

// Div returns m/x
func (m Mint) Div(x Mint) Mint {
	return m.Mul(x.Inv())
}

// AddAs assigns *m + x to *m and returns m
func (m *Mint) AddAs(x Mint) *Mint {
	*m = m.Add(x)
	return m
}

// SubAs assigns *m - x to *m and returns m
func (m *Mint) SubAs(x Mint) *Mint {
	*m = m.Sub(x)
	return m
}

// MulAs assigns *m * x to *m and returns m
func (m *Mint) MulAs(x Mint) *Mint {
	*m = m.Mul(x)
	return m
}

// DivAs assigns *m / x to *m and returns m
func (m *Mint) DivAs(x Mint) *Mint {
	*m = m.Div(x)
	return m
}