BOJ_2579.java

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main {
    public static void main(String args[]) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int N = Integer.parseInt(br.readLine());
        int s[] = new int [N + 2];
        int d[] = new int[N + 2];

        for(int i = 1; i <= N; i++) {
            s[i] = Integer.parseInt(br.readLine());
        }

        d[1] = s[1];
        d[2] = s[1] + s[2];
        for(int i = 3; i <= N; i++) {
            d[i] = Math.max(d[i - 2], d[i - 3] + s[i - 1]) + s[i];
        }
        System.out.println(d[N]);
    }
}