object Main extends App {
	import scala.math._

	val n = scala.io.StdIn.readInt
	val a1 = scala.io.StdIn.readLine.split(" ").map(_.toInt)
	val a2 = scala.io.StdIn.readLine.split(" ").map(_.toInt)

	var ans = 0

	if(n==1) ans = a1.sum + a2.sum

	for(i<-1 until n){
		println(a1.dropRight(n-i).mkString(" "))
		println(a2.drop(i).mkString(" "))
		ans = max(ans, a1.dropRight(n-i).sum + a2.drop(i-1).sum)
	}

	println(ans)
}