func main()
	var k: int :: cui@inputInt()
	var n: int :: cui@inputInt()
	var f: int :: cui@inputInt()
	var a: []int :: #[f]int
	for i(0, f - 1)
		do a[i] :: cui@inputInt()
	end for
	
	var ans: int :: k * n
	for i(0, f - 1)
		do ans :- a[i]
	end for
	do ans :: [ans, -1].max()
	do cui@print("\{ans}\n")
end func