#include<iostream.h>
#include<math.h>
#include<limits.h>
main()
{
    long D,U,i,sum,crno,minN,j;
    double min,ratio,nouse;
    int flag=0;
    cin>>D>>U;
    min=1000000;
    minN=D;
    for(long t=1000000;t>=2;t--)
    {
        U=t;
    if(D==1)
        cout<<'0';
    else
    {
        for(i=U;i>=D;i--)
        {
            sum=1;

            for(j=2;j<=sqrt((double)i);j++)
            {
                if(i%j==0)
                {
                    sum+=j+i/j;
                }
            }
            if(i%(j-1)==0)
                sum-=j;

            ratio=double(sum)/(double)i;
            if(ratio<=min)
            {

                min=ratio;
                minN=i;
                if(sum==1)
                {
                    for(long k=U;k>=D;k--)
                    {

                        if(modf(sqrt((double)k),&nouse)==0)
                        {
                            ratio=(1+sqrt((double)k))/(double)k;
                            if(ratio>min)
                                break;
                            else
                            {

                                min=k;
                                minN=k;
                                break;
                            }
                        }
                    }
                    break;
                }

            }
        }
        cout<<minN;
    }
    }
}