def fact(c)
    ret = 1
    
    for i in 2..c do
    	ret *= i
    end
    
    return ret
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