using System;
using System.Collections.Generic;
using System.Windows;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Atcoder
{
    public class Program
    {
        private static long mod = 1000000007;

        static void Main(string[] args)
        {
            var n = Read().Long();
            max = n;
            Dfs(0, 0, 0, 0, 3);
            Dfs(0, 0, 0, 0, 5);
            Dfs(0, 0, 0, 0, 7);
            WriteRead(count);
        }

        private static int count = 0;
        private static long max = 0;
        private static void Dfs(long now, int flg1, int flg2, int flg3, long next)
        {
            now = now * 10 + next;
            if (max < now)
            {
                return;
            }
            if (next == 3)
            {
                flg1 = 1;
            }
            else if (next == 5)
            {
                flg2 = 1;
            }
            else if (next == 7)
            {
                flg3 = 1;
            }
            if (flg1 == 1 && flg2 == 1 && flg3 == 1)
            {
                count++;
            }
            Dfs(now, flg1, flg2, flg3, 3);
            Dfs(now, flg1, flg2, flg3, 5);
            Dfs(now, flg1, flg2, flg3, 7);
        }

        public static IEnumerable<int> PrimeFactors(int n)
        {
            int i = 2;
            int tmp = n;

            while (i * i <= n) //※1
            {
                if (tmp % i == 0)
                {
                    tmp /= i;
                    yield return i;
                }
                else
                {
                    i++;
                }
            }
            if (tmp != 1) yield return tmp;//最後の素数も返す
        }

        public static string Read()
        {
            return Console.ReadLine();
        }

        public static string[] ReadSplit()
        {
            return Console.ReadLine().Split(' ');
        }

        public static void WriteRead(object str)
        {
            Console.WriteLine(str);
            Read();
        }

        public static void Write(object str)
        {
            Console.WriteLine(str);
        }

        private static bool ChangeMin<T>(ref T a, T b) where T : IComparable
        {
            if (a.CompareTo(b) > 0)
            {
                a = b;
                return true;
            }
            return false;
        }

        private static bool ChangekMax<T>(ref T a, T b) where T : IComparable
        {
            if (b.CompareTo(a) > 0)
            {
                a = b;
                return true;
            }
            return false;
        }
    }
}


public static class Extentions
{
    public static int Int(this object obj)
    {
        return int.Parse(obj.ToString());
    }

    public static long Long(this object obj)
    {
        return long.Parse(obj.ToString());
    }

    public static decimal Decimal(this object obj)
    {
        return decimal.Parse(obj.ToString());
    }

    public static double Double(this object obj)
    {
        return double.Parse(obj.ToString());
    }

    public static T2 GetValueZero<T1, T2>(this Dictionary<T1, T2> d, T1 key) where T2 : struct
    {
        T2 value;
        if (d.TryGetValue(key, out value))
        {
            return value;
        }
        return new T2();
    }
}



Measured memory_bytes: 13140