using System;
using System.Collections.Generic;
using System.IO;
using System.Collections;

namespace Decomposition
{
    class Program
    {
        static void Main(string[] args)
        {
            int a, b, c;
            Init(out a, out b, out c);
            if (a >= b && a <= c)
            {
                WriteInt(1);
                return;
            }
            ArrayList denominators = new ArrayList();
            Fill(denominators, a);

            int indLeftBorder = -1;
            int indRightBorder = - 1;
            getRange(denominators, b, c, ref indLeftBorder, ref indRightBorder);


            Dictionary<int, int> NumOfWays = new Dictionary<int, int>();
            for (int i = 0; i < denominators.Count; i++)
                NumOfWays[(int)denominators[i]] = 0;
            int min = 0;

            GetWays(denominators, a, b, c, indLeftBorder, indLeftBorder, NumOfWays, ref min);

            FindMin(denominators, indLeftBorder, indLeftBorder, NumOfWays, min);


            return;

        }

        static void Init(out int a, out int b, out int c)
        {
            FileStream fin = new FileStream("input.txt", FileMode.OpenOrCreate);
            StreamReader fRead = new StreamReader(fin);

            string[] buff = fRead.ReadLine().Split(' ');
            fRead.Close();
            a = Int32.Parse(buff[0]);
            b = Int32.Parse(buff[1]);
            c = Int32.Parse(buff[2]);
        }

        static void Fill(ArrayList denominators, int a)
        {
            for (int i = 1; i <= Math.Sqrt(a); i++)
            {
                if (a % i == 0)
                    denominators.Add(i);
            }
            for (int i = denominators.Count - 1; i >= 0; i--)
                denominators.Add(a / (int)denominators[i]);
        }

        static void getRange(ArrayList denominators, int b, int c, ref int indLeftBorder, ref int indRightBorder)
        {
            for (int i = 0; i < denominators.Count; i++)
            {
                if ((int)denominators[i] >= b)
                {
                    indLeftBorder = i;
                    break;
                }
            }
            for (int i = denominators.Count - 1; i >= 0; i--)
            {
                if ((int)denominators[i] <= c)
                {
                    indRightBorder = i;
                    break;
                }
            }
            if (b == 1)
                indLeftBorder++;
            if (indRightBorder < indLeftBorder)
            {
                WriteInt(-1);
                return;
            }
        }

        static void WriteInt(int answer)
        {
            FileStream fout = new FileStream("output.txt", FileMode.OpenOrCreate);
            StreamWriter fWrite = new StreamWriter(fout);

            fWrite.Write(answer.ToString());
            fWrite.Close();
        }

        static void GetWays(ArrayList denominators, int a, int b, int c, int indLeftBorder,
            int indRightBorder, Dictionary<int, int> numOfWays, ref int min)
        {
            for (int i = indRightBorder; a > c;)
            {
                if ((i == denominators.Count - 1) || numOfWays[a] > 0)
                {
                    for (int j = indLeftBorder; j <= indRightBorder; j++)
                    {
                        if (a % (int)denominators[j] == 0)
                        {
                            int buff = a / (int)denominators[j];
                            if (numOfWays[buff] == 0 || numOfWays[buff] > numOfWays[a] + 1)
                                numOfWays[buff] = numOfWays[a] + 1;
                            if (buff >= b && buff <= c)
                                min = numOfWays[buff];
                        }
                    }
                }
                a = (int)denominators[--i];
            }
        }

        static void FindMin(ArrayList denominators, int indLeftBorder,
            int indRightBorder, Dictionary<int, int> Steps, int min)
        {
            if (min != 0)
            {
                for (int i = indLeftBorder; i <= indRightBorder; i++)
                {
                    if (Steps[(int)denominators[i]] < min && Steps[(int)denominators[i]] > 0)
                        min = Steps[(int)denominators[i]];
                }
                WriteInt(min + 1);
                return;
            }
            WriteInt(-1);
        }
    }
}