const val MOD = 1000000007
fun main() {
    val (n, target, k) = readLine()!!.trim().split(' ').map(String::toInt)
    val initial = n * (n - 1) / 2 * k
    if (initial !in 0 .. target) {
        println(0)
        return
    }
    val memo = IntArray(target - initial + 1).also{it[0] = 1}
    for (i in 0 until n) {
        val rest = n - i
        for (j in 0 .. memo.lastIndex - rest) {
            memo[j + rest] = (memo[j + rest] + memo[j]) % MOD
        }
    }
    println(memo.last())
}