import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {
    static long move=0;
    static void count(long l,long r)
    {  long k,t,p;
        
        if((r-l)%2==0)
        {
           k=(r-l)/2;
            move=move+k*3+1;
        }
     else
     {
             if(r-l==1)
             {move=move+1;}
             else
             {
                 move=move+(r-l)+1;
             }
         
     }
    }
    
    static long longestSequence(long[] a) {
        //  Return the length of the longest possible sequence of moves.
        for(int i=0;i<a.length;i++)
        {count(0,a[i]);
         //System.out.println("move"+move);
        }
        return move;
    }

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        long[] a = new long[n];
        for(int a_i = 0; a_i < n; a_i++){
            a[a_i] = in.nextLong();
        }
        long result = longestSequence(a);
        System.out.println(result);
        in.close();
    }
}