using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

​

namespace MultiplyIfDividedBy7

{

    public class MultiplyIfDividedBy7

    {

        public static void Main(string[] args)

        {

            int n = int.Parse(Console.ReadLine()),

                result = 1,

                count = 0;

            int[] numbers = new int[n];

            Console.WriteLine();

​

            for (int i = 0; i < numbers.Length; i++)

            {

                numbers[i] = int.Parse(Console.ReadLine());

                if (numbers[i] % 7 == 0  && numbers[i] != 0)

                {

                    result *= numbers[i];

                    count += 1;

                }

            }

​

            Console.WriteLine(count > 0 ? result.ToString() : "No");

        }

    }

}

​