fun main() {
    val (a, b, s) = readLongs()
    var ans = 0L
    for (x in 1..a) {
        for (y in 1..b) {
            if (x * y > s) break
            ans += (a - x + 1) * (b - y + 1)
        }
    }
    println(ans)
}

fun readLongs() = readln().split(" ").map { it.toLong() }