#!/usr/bin/env ruby
#coding: utf-8

n, m, r = gets.split.map(&:to_i)
r -= n * m
if (r < 0) 
  puts 0
else
  ans = 1
  (r + 1).upto(n + r - 1) do |i|
    ans *= i
  end
  1.upto(n - 1) do |i|
    ans /= i
  end
  puts ans
end