import java.util.Arrays;
import java.util.Scanner;


public class T1025 {

    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        int k=sc.nextInt();
        int [] a=new int[k];
        for(int i=0;i<k;i++)
        {
            a[i]=sc.nextInt();
        }
        Arrays.sort(a);
        int vote=0;
        int mid=k%2==0?k/2:k/2+1;
        for(int i=0;i<mid;i++)
        {
            vote+=a[i]/2+1;
        }
        System.out.println(vote);

    }

}