#include <iostream>

using namespace std;

int st,dr,n,i;

int cmmdc(int a,int b)
{
    while (b>0)
    {
        int r=a%b;
        a=b;
        b=r;
    }
    return a;

}

int main()
{
    cin>>st>>dr;

    if(cmmdc(st,dr)==1)
    {
        cout<<dr-st+1;
        return 0;
    }
    int n=(dr/st-1)*st+1;

    for(i=dr-1;i>=n;i--)
    {
        if(cmmdc(st,i)==1)
        {
            cout<<i-st+1;
            return 0;
        }
    }


    return 0;
}