func main()
	var ss: [][]char
	do ss :: cui@input().split(" ")
	var K: int :: ss[0].toInt(&)
	var N: int :: ss[1].toInt(&)
	var F: int :: ss[2].toInt(&)
	var A: []int :: #[F]int
	do ss :: cui@input().split(" ")
	for i(0, F - 1)
		do A[i] :: ss[i].toInt(&)
	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