def fact(i)
    if i == 0 then
        return 1
    end
    
    return i * fact(i - 1)
end

n, m, r = gets.split.map(&:to_i)

r = r - n * m
m = 0

if r < 0 then
	puts "0"
else
	p fact(n + r - 1) / fact(n - 1) / fact(r)
end