import java.util.*;

public class Main {
	public static void main (String[] args) {
    	Scanner sc = new Scanner(System.in);
    	int n = sc.nextInt();
    	int[] base = new int[n + 1];
    	int[] sums = new int[n + 1];
    	for (int i = 1; i <= n; i++) {
    	    base[i] = sc.nextInt();
    	    sums[i] = sums[i - 1] + base[i] / 2;
    	}
    	int max = 0;
    	for (int i = 1; i <= n; i++) {
    	    max = Math.max(max, base[i] + sums[i - 1] + sums[n] - sums[i]);
    	}
    	System.out.println(max);
	}
}