#include <iostream>
#include <fstream>
using namespace std;
char prim[10000000];
int main()
{
    int a, b, pp=0, sp=0, maxim=0, v[2]={0,0};
    ifstream in("difprim.in");
    in>>a;
    in>>b;
    in.close();
    for(int i=2;i*i<=b;i++)
    {
        if(prim[i]==0)
        {
            for(int j=i*i;j<=b;j+=i)
            {
                prim[j]=1;
            }
        }
    }
    for(int i=a;i<=b;i++)
    {
        if(prim[i]==0)
        {
            int ci=i;
            ci++;
            while(prim[ci]!=0)
            {
                ci++;
            }
            if(prim[i]==0  && prim[ci]==0 && ci<=b)
            {
                pp=i;
                sp=ci;
            }
            if(sp-pp>maxim)
                {v[0]=pp;
                v[1]=sp;
                maxim=sp-pp;}
        }
    }
    ofstream out;
    out.open("difprim.out");
    if(v[0]==0||v[1]==0)
        out<<-1;
    else
    {
        out<<v[0]<<" "<<v[1];
    }
    out.close();
    return 0;
}