using System;
using System.Collections.Generic;
using System.Linq;

namespace yukicoder
{
    public class Program
    {
        public static void Main()
        {
            var s = Console.ReadLine().Split(' ').Select(x => int.Parse(x)).ToArray();
            var sum = 0;
            sum = Make(s, sum);
            Console.WriteLine(sum);
        }
        public static int Make(int[] s,int sum)
        {
            Array.Sort(s);
            sum += s[0];
            s = s.Select(x => x - s[0]).Where(x => x > 0).ToArray();
            while (s.All(x => x > 0))
            {
                Array.Sort(s);
                s[0]--;
                s[1] -= 3;
                sum++;
            }
            while (s[1] > 4)
            {
                s[1] -= 5;
                sum++;
            }
            return sum;
        }
    }
}