using System;
using System.Linq;
using System.Collections.Generic;
using Debug = System.Diagnostics.Debug;
using StringBuilder = System.Text.StringBuilder;
using System.Numerics;
using Point = System.Numerics.Complex;
namespace Program
{

    public class Solver
    {
        bool[] primes = MathEx.Sieve(20000);
        public void Solve()
        {
            //Write(17, 8);

            var s = sc.Scan();

            if (s.Length <= 3)
            {
                var v = int.Parse(s);
                for (int i = 3; i < v; i++)
                {
                    var k = (v + i - 1) / i;
                    var bucket = Enumerate(k, x => new char[i]);
                    var set = new DisjointSet(v);
                    for (int j = 0; j < v; j++)
                    {
                        bucket[j / i][j % i] = (primes[j + 1]) ? 'x' : 'o';
                        if (primes[j + 1]) continue;
                        var u = (j / i - 1);

                        if (u >= 0 && !primes[j + 1 - i])
                            set.Unite(j, j - i);
                        if (j % i > 0 && !primes[j])
                            set.Unite(j, j - 1);
                    }
                    //foreach (var x in bucket) IO.Printer.Out.WriteLine(x.AsString());
                    if (set.IsUnited(0, v - 1))
                    {
                        IO.Printer.Out.WriteLine(i);
                        return;
                    }
                }
            }
            else
            {
                var v = BigInteger.Parse(s) - 8;
                if (v % 8 != 1)
                {

                    IO.Printer.Out.WriteLine(8);
                }
                else
                {
                    long u;
                    if (long.TryParse(s, out u) && isPrime(u - 8))
                    {

                        IO.Printer.Out.WriteLine(14);

                    }
                    else IO.Printer.Out.WriteLine(8);
                }

            }

        }


        static public long ModPow(long x, long n, long mod)
        {
            long r = 1;
            while (n > 0)
            {
                if ((n & 1) == 1)
                    r = r * x % mod;
                x = (x * x) % mod;
                n >>= 1;
            }
            return r;
        }
        bool suspect(long a, long s, long d, long n)
        {
            var x = ModPow(a, d, n);
            if (x == 1) return true;
            for (int r = 0; r < s; ++r)
            {
                if (x == n - 1) return true;
                x = x * x % n;
            }
            return false;
        }
        // {2,7,61,-1}                 is for n < 4759123141 (= 2^32)
        // {2,3,5,7,11,13,17,19,23,-1} is for n < 10^16 (at least)
        bool isPrime(long n)
        {
            if (n >= 5000000000000000) return true;
            for (long u = 2; u * u <= n; u++)
            {
                if (n % u == 0) return false;
            }
            return true;
            /*
            if (n <= 1 || (n > 2 && n % 2 == 0)) return false;
            var test = new int[] { 2, 3, 5, 7, 11, 13, 17, 19, 23, -1 };
            long d = n - 1, s = 0;
            while (d % 2 == 0) { ++s; d /= 2; }
            for (int i = 0; test[i] < n && test[i] != -1; ++i)
                if (!suspect(test[i], s, d, n)) return false;
            return true;
            */
        }

        public void Write(int v, int i)
        {
            var k = (v + i - 1) / i;
            var bucket = Enumerate(k, x => new char[i]);
            var set = new DisjointSet(v);
            for (int j = 0; j < v; j++)
            {
                bucket[j / i][j % i] = (primes[j + 1]) ? 'x' : 'o';
                if (primes[j + 1]) continue;
                var u = (j / i - 1);

                if (u >= 0 && !primes[j + 1 - i])
                    set.Unite(j, j - i);
                if (j % i > 0 && !primes[j])
                    set.Unite(j, j - 1);
            }
            IO.Printer.Out.WriteLine("{0} {1}", v, i);
            foreach (var x in bucket) IO.Printer.Out.WriteLine(x.AsString());

        }
        public IO.StreamScanner sc = new IO.StreamScanner(Console.OpenStandardInput());
        static T[] Enumerate<T>(int n, Func<int, T> f) { var a = new T[n]; for (int i = 0; i < n; ++i) a[i] = f(i); return a; }
        static public void Swap<T>(ref T a, ref T b) { var tmp = a; a = b; b = tmp; }
    }
}

#region Ex
namespace Program.IO
{
    using System.IO;
    using System.Text;
    using System.Globalization;
    public class Printer : StreamWriter
    {
        static Printer() { Out = new Printer(Console.OpenStandardOutput()) { AutoFlush = false }; }
        public static Printer Out { get; set; }
        public override IFormatProvider FormatProvider { get { return CultureInfo.InvariantCulture; } }
        public Printer(System.IO.Stream stream) : base(stream, new UTF8Encoding(false, true)) { }
        public Printer(System.IO.Stream stream, Encoding encoding) : base(stream, encoding) { }
        public void Write<T>(string format, IEnumerable<T> source) { base.Write(format, source.OfType<object>().ToArray()); }
        public void WriteLine<T>(string format, IEnumerable<T> source) { base.WriteLine(format, source.OfType<object>().ToArray()); }
    }
    public class StreamScanner
    {
        public StreamScanner(Stream stream) { str = stream; }
        public readonly Stream str;
        private readonly byte[] buf = new byte[1024];
        private int len, ptr;
        public bool isEof = false;
        public bool IsEndOfStream { get { return isEof; } }
        private byte read()
        {
            if (isEof) return 0;
            if (ptr >= len) { ptr = 0; if ((len = str.Read(buf, 0, 1024)) <= 0) { isEof = true; return 0; } }
            return buf[ptr++];
        }
        public char Char() { byte b = 0; do b = read(); while ((b < 33 || 126 < b) && !isEof); return (char)b; }

        public string Scan()
        {
            var sb = new StringBuilder();
            for (var b = Char(); b >= 33 && b <= 126; b = (char)read())
                sb.Append(b);
            return sb.ToString();
        }
        public long Long()
        {
            if (isEof) return long.MinValue;
            long ret = 0; byte b = 0; var ng = false;
            do b = read();
            while (b != '-' && (b < '0' || '9' < b));
            if (b == '-') { ng = true; b = read(); }
            for (; true; b = read())
            {
                if (b < '0' || '9' < b)
                    return ng ? -ret : ret;
                else ret = ret * 10 + b - '0';
            }
        }
        public int Integer() { return (isEof) ? int.MinValue : (int)Long(); }
        public double Double() { return double.Parse(Scan(), CultureInfo.InvariantCulture); }
        private T[] enumerate<T>(int n, Func<T> f)
        {
            var a = new T[n];
            for (int i = 0; i < n; ++i) a[i] = f();
            return a;
        }

        public char[] Char(int n) { return enumerate(n, Char); }
        public string[] Scan(int n) { return enumerate(n, Scan); }
        public double[] Double(int n) { return enumerate(n, Double); }
        public int[] Integer(int n) { return enumerate(n, Integer); }
        public long[] Long(int n) { return enumerate(n, Long); }
    }
}

static class Ex
{
    static public string AsString(this IEnumerable<char> ie) { return new string(System.Linq.Enumerable.ToArray(ie)); }
    static public string AsJoinedString<T>(this IEnumerable<T> ie, string st = " ") { return string.Join(st, ie); }
    static public void Main()
    {
        var solver = new Program.Solver();
        solver.Solve();
        Program.IO.Printer.Out.Flush();
    }
}
#endregion
#region sieve
static public partial class MathEx
{
    static public bool[] Sieve(int p)
    {
        var isPrime = new bool[p + 1];
        for (int i = 2; i <= p; i++) isPrime[i] = true;
        for (int i = 2; i * i <= p; i++)
            if (!isPrime[i]) continue;
            else
                for (int j = i * i; j <= p; j += i)
                    isPrime[j] = false;
        return isPrime;
    }
}
#endregion
#region DisjointSet
public class DisjointSet
{
    public int[] par, ranks, count;
    public DisjointSet(int n)
    {
        par = new int[n];
        count = new int[n];
        for (int i = 0; i < n; i++)
        {
            par[i] = i;
            count[i] = 1;
        }
        ranks = new int[n];
    }
    public int this[int id] { get { return (par[id] == id) ? id : this[par[id]]; } }
    public bool Unite(int x, int y)
    {
        x = this[x]; y = this[y];
        if (x == y) return false;
        if (ranks[x] < ranks[y])
        {
            par[x] = y;
            count[y] += count[x];
        }
        else
        {
            par[y] = x;
            count[x] += count[y];
            if (ranks[x] == ranks[y])
                ranks[x]++;
        }
        return true;
    }
    public int Size(int x) { return count[this[x]]; }
    public bool IsUnited(int x, int y) { return this[x] == this[y]; }

}
#endregion