using System;
using System.Linq;
using CompLib.Util;
using System.Threading;
using CompLib.DataStructure;
using CompLib.Mathematics;

public class Program
{
    private int L, R;

    public void Solve()
    {
        var sc = new Scanner();
        L = sc.NextInt();
        R = sc.NextInt();

        int e = 0;
        var uf = new UnionFind(R + 1);

        long ans = 0;
        for (int m = 0; e < R - L; m++)
        {
            for (int i = L; i <= R && e < R - L; i++)
            {
                for (int j = i + m; j <= R && e < R - L; j += i)
                {
                    if (uf.Connect(i, j))
                    {
                        e++;
                        ans += m;
                    }
                }
            }
        }

        Console.WriteLine(ans);
    }

    public static void Main(string[] args) => new Program().Solve();
    // public static void Main(string[] args) => new Thread(new Program().Solve, 1 << 27).Start();
}

namespace CompLib.DataStructure
{
    using System.Collections.Generic;
    using System.Linq;

    class UnionFind
    {
        private readonly int _n;
        private readonly int[] _parent, _size;

        /// <summary>
        /// n頂点の無向グラフに 1.辺を追加, 2.2頂点が同じ連結成分に属するか判定 ができるデータ構造
        /// </summary>
        /// <param name="n">頂点の個数</param>
        public UnionFind(int n)
        {
            _n = n;
            _parent = new int[_n];
            _size = new int[_n];
            for (int i = 0; i < _n; i++)
            {
                _parent[i] = i;
                _size[i] = 1;
            }
        }

        /// <summary>
        /// iがいる連結成分の代表値
        /// </summary>
        /// <param name="i"></param>
        /// <returns></returns>
        public int Find(int i) => _parent[i] == i ? i : Find(_parent[i]);

        /// <summary>
        /// x,yが同じ連結成分にいるか?
        /// </summary>
        /// <param name="x"></param>
        /// <param name="y"></param>
        /// <returns></returns>
        public bool Same(int x, int y) => Find(x) == Find(y);

        /// <summary>
        /// (x, y)に辺を追加する
        /// </summary>
        /// <remarks>
        /// ACLでは連結された代表値を返しますが、ここでは連結できたか?を返します
        /// </remarks>
        /// <param name="x"></param>
        /// <param name="y"></param>
        /// <returns>x,yが違う連結成分だったならtrueを返す</returns>
        public bool Connect(int x, int y)
        {
            x = Find(x);
            y = Find(y);
            if (x == y) return false;

            // データ構造をマージする一般的なテク
            if (_size[x] > _size[y])
            {
                _parent[y] = x;
                _size[x] += _size[y];
            }
            else
            {
                _parent[x] = y;
                _size[y] += _size[x];
            }

            return true;
        }

        /// <summary>
        /// iが含まれる成分のサイズ
        /// </summary>
        /// <param name="i"></param>
        /// <returns></returns>
        public int GetSize(int i) => _size[Find(i)];

        /// <summary>
        /// 連結成分のリスト
        /// </summary>
        /// <returns></returns>
        public List<int>[] Groups()
        {
            var leaderBuf = new int[_n];
            var groupSize = new int[_n];
            for (int i = 0; i < _n; i++)
            {
                leaderBuf[i] = Find(i);
                groupSize[leaderBuf[i]]++;
            }

            var result = new List<int>[_n];
            for (int i = 0; i < _n; i++)
            {
                result[i] = new List<int>(groupSize[i]);
            }

            for (int i = 0; i < _n; i++)
            {
                result[leaderBuf[i]].Add(i);
            }

            return result.Where(ls => ls.Count > 0).ToArray();
        }
    }
}


// https://bitbucket.org/camypaper/complib
namespace CompLib.Mathematics
{
    using System;
    using System.Collections.Generic;

    #region GCD LCM

    /// <summary>
    /// 様々な数学的関数の静的メソッドを提供します．
    /// </summary>
    public static partial class MathEx
    {
        /// <summary>
        /// 2 つの整数の最大公約数を求めます．
        /// </summary>
        /// <param name="n">最初の値</param>
        /// <param name="m">2 番目の値</param>
        /// <returns>2 つの整数の最大公約数</returns>
        /// <remarks>ユークリッドの互除法に基づき最悪計算量 O(log N) で実行されます．</remarks>
        public static int GCD(int n, int m)
        {
            return (int) GCD((long) n, m);
        }


        /// <summary>
        /// 2 つの整数の最大公約数を求めます．
        /// </summary>
        /// <param name="n">最初の値</param>
        /// <param name="m">2 番目の値</param>
        /// <returns>2 つの整数の最大公約数</returns>
        /// <remarks>ユークリッドの互除法に基づき最悪計算量 O(log N) で実行されます．</remarks>
        public static long GCD(long n, long m)
        {
            n = Math.Abs(n);
            m = Math.Abs(m);
            while (n != 0)
            {
                m %= n;
                if (m == 0) return n;
                n %= m;
            }

            return m;
        }


        /// <summary>
        /// 2 つの整数の最小公倍数を求めます．
        /// </summary>
        /// <param name="n">最初の値</param>
        /// <param name="m">2 番目の値</param>
        /// <returns>2 つの整数の最小公倍数</returns>
        /// <remarks>最悪計算量 O(log N) で実行されます．</remarks>
        public static long LCM(long n, long m)
        {
            return (n / GCD(n, m)) * m;
        }
    }

    #endregion

    #region PrimeSieve

    public static partial class MathEx
    {
        /// <summary>
        /// ある値までに素数表を構築します．
        /// </summary>
        /// <param name="max">最大の値</param>
        /// <param name="primes">素数のみを入れた数列が返される</param>
        /// <returns>0 から max までの素数表</returns>
        /// <remarks>エラトステネスの篩に基づき，最悪計算量 O(N loglog N) で実行されます．</remarks>
        public static bool[] Sieve(int max, List<int> primes = null)
        {
            var isPrime = new bool[max + 1];
            for (int i = 2; i < isPrime.Length; i++) isPrime[i] = true;
            for (int i = 2; i * i <= max; i++)
                if (!isPrime[i]) continue;
                else
                    for (int j = i * i; j <= max; j += i)
                        isPrime[j] = false;
            if (primes != null)
                for (int i = 0; i <= max; i++)
                    if (isPrime[i])
                        primes.Add(i);

            return isPrime;
        }
    }

    #endregion
}

namespace CompLib.Util
{
    using System;
    using System.Linq;

    class Scanner
    {
        private string[] _line;
        private int _index;
        private const char Separator = ' ';

        public Scanner()
        {
            _line = new string[0];
            _index = 0;
        }

        public string Next()
        {
            if (_index >= _line.Length)
            {
                string s;
                do
                {
                    s = Console.ReadLine();
                } while (s.Length == 0);

                _line = s.Split(Separator);
                _index = 0;
            }

            return _line[_index++];
        }

        public string ReadLine()
        {
            _index = _line.Length;
            return Console.ReadLine();
        }

        public int NextInt() => int.Parse(Next());
        public long NextLong() => long.Parse(Next());
        public double NextDouble() => double.Parse(Next());
        public decimal NextDecimal() => decimal.Parse(Next());
        public char NextChar() => Next()[0];
        public char[] NextCharArray() => Next().ToCharArray();

        public string[] Array()
        {
            string s = Console.ReadLine();
            _line = s.Length == 0 ? new string[0] : s.Split(Separator);
            _index = _line.Length;
            return _line;
        }

        public int[] IntArray() => Array().Select(int.Parse).ToArray();
        public long[] LongArray() => Array().Select(long.Parse).ToArray();
        public double[] DoubleArray() => Array().Select(double.Parse).ToArray();
        public decimal[] DecimalArray() => Array().Select(decimal.Parse).ToArray();
    }
}