import std.stdio, std.conv, std.string, std.bigint;
import std.math, std.random, std.datetime;
import std.array, std.range, std.algorithm, std.container;
string read(){ static string[] ss; while(!ss.length) ss = readln.chomp.split; string res = ss[0]; ss.popFront; return res; }

void main(){
	int n = read.to!int;
	int[] vs = readln.chomp.split.map!(to!int).array;
	
	int a, b;
	a = vs[0], b = 0;
	for(int i = 1; i < n; i ++){
		int a2, b2;
		if(a > b) b2 = a; else b2 = b;
		a2 = b + vs[i];
		
		a = a2, b = b2;
	}
	if(a > b) a.writeln; else b.writeln;
}