using System;
using System.Text;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
using static System.Console;
using static System.Math;

namespace ABC114C
{
    public class Program
    {
        public static void Main(string[] args)
        {
            new Program().Solve(new ConsoleInput(Console.In, ' '));

            return;
        }

        public void Solve(ConsoleInput cin)
        {

            var N = cin.ReadInt;

            if (N < 357)
            {
                Console.WriteLine(0);
                return;
            }

            var NLength = N.ToString().Length;

            int ans = 0;
            for (int numLength = 3; numLength <= NLength; numLength++)
            {
                var dfs = new Dfs(N, numLength);
                dfs.Proc(0, 3);
                dfs.Proc(0, 5);
                dfs.Proc(0, 7);
                ans += dfs.Ans();
            }

            Console.WriteLine(ans);

        }
        public class Dfs
        {
            private readonly int N;
            private readonly int numLength;
            private int pattern;
            public Dfs(int N, int numLength)
            {
                this.N = N;
                this.numLength = numLength;
            }
            public int Ans()
            {
                return this.pattern;
            }
            public bool Proc(int cur, int num)
            {
                cur++;
                if(cur == this.numLength)
                {
                    if(num <= this.N)
                    {
                        var numCharArray = num.ToString().ToCharArray();
                        if (numCharArray.Contains('3')
                            && numCharArray.Contains('5')
                            && numCharArray.Contains('7'))
                        {
                            this.pattern++;
                        }
                    }
                    return true;
                }
                this.Proc(cur, num + (int)Pow(10, cur) * 3);
                this.Proc(cur, num + (int)Pow(10, cur) * 5);
                this.Proc(cur, num + (int)Pow(10, cur) * 7);
                return false;
            }
        }
    }

    public static class Extensions
    {
        public static string Reverse(this string sourse)
        {
            char[] chrAry = sourse.ToCharArray();
            Array.Reverse(chrAry);
            return new string(chrAry);
        }
    }

    public class ConsoleInput
    {
        private readonly System.IO.TextReader _stream;
        private char _separator = ' ';
        private Queue<string> inputStream;
        public ConsoleInput(System.IO.TextReader stream, char separator = ' ')
        {
            this._separator = separator;
            this._stream = stream;
            inputStream = new Queue<string>();
        }
        public string Read
        {
            get
            {
                if (inputStream.Count != 0) return inputStream.Dequeue();
                string[] tmp = _stream.ReadLine().Split(_separator);
                for (int i = 0; i < tmp.Length; ++i)
                    inputStream.Enqueue(tmp[i]);
                return inputStream.Dequeue();
            }
        }
        public string ReadLine { get { return _stream.ReadLine(); } }
        public int ReadInt { get { return int.Parse(Read); } }
        public long ReadLong { get { return long.Parse(Read); } }
        public double ReadDouble { get { return double.Parse(Read); } }
        public string[] ReadStrArray(long N) { var ret = new string[N]; for (long i = 0; i < N; ++i) ret[i] = Read; return ret; }
        public int[] ReadIntArray(long N) { var ret = new int[N]; for (long i = 0; i < N; ++i) ret[i] = ReadInt; return ret; }
        public long[] ReadLongArray(long N) { var ret = new long[N]; for (long i = 0; i < N; ++i) ret[i] = ReadLong; return ret; }
    }
}


Measured memory_bytes: 15436