#include <iostream>

using namespace std;
int D[100],sol,i,a,b;
int main()
{

    D[2] = D[3] = D[5] = D[7] = D[23] = D[37] = 1;
    cin>>a>>b;
    for(i=a;i<=b && i<=37;i++)
        sol+=D[i];
    cout<<sol;

    return 0;
}