import java.util.Scanner;
public class Main {
    public static void main(String args[]) {
        try {
            Scanner in = new Scanner(System.in);

            int[] group = new int[in.nextInt()];
            for(int i=0; i<group.length; i++) {
                group[i] = in.nextInt();
            }
            int per;
            for(int i=0; i<group.length - 1; i++) {
                for(int j=1; j<group.length; j++) {
                    if (group[i] >= group[j]) {
                        per = group[i];
                        group[i] = group[j];
                        group[j] = per;
                    }
                }
            }
            int sum = 0;
            for(int i=0; i<group.length/2 + 1; i++) {
                sum += group[i]/2 + 1;
            }
            System.out.println(sum);
            in.close();
        }
        catch(Exception e) {
            System.out.println("Error");
        }
    }
}