import java.util.*;
public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
		List<Long> list = new ArrayList<Long>();
        for(int i = 0 ; i < n ; i++){
        	list.add(scan.nextLong());
        }
        long remainder = 1000000007;
        while(list.size() > 1){
        	List<Long> listCopy = new ArrayList<Long>();
        	for(int i = 0 ; i < list.size()-1 ; i++){
        		listCopy.add((list.get(i) + list.get(i+1)) % remainder);
        	}
        	list = listCopy;
        }
        System.out.println(list.get(0));
    }
}