import std.stdio, std.conv, std.string, std.array, std.range, std.algorithm, std.container;
import std.math, std.random, std.bigint, std.datetime, std.format;
void main(string[] args){ if(args.length > 1) if(args[1] == "-debug") DEBUG = 1; solve(); }
void log()(){ writeln(""); } void log(T, A ...)(T t, lazy A a){ if(DEBUG) write(t, " "), log(a); } bool DEBUG = 0; 
string read(){ static string[] ss; while(!ss.length) ss = readln.chomp.split; string res = ss[0]; ss.popFront; return res; }
// ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- //

void solve(){
	int n = read.to!int;
	long[] as, bs;
	foreach(i; 0 .. n) as ~= read.to!long;
	foreach(i; 0 .. n) bs ~= read.to!long;
	
	long[] xs, ys;
	foreach(i; 0 .. n){
		if(i == 0) xs ~= as[0], ys ~= bs[0];
		else{
			xs ~= max(ys[i - 1] + as[i], xs[i - 1]);
			ys ~= max(xs[i - 1] + bs[i], ys[i - 1]);
		}
	}
	
	long ans = max(xs[n - 1], ys[n - 1]);
	ans.writeln;
	
}
