import java.util.*;

public class Main {

    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt();
        solve(a,b);
    }
    
    static void solve(int a, int b) {
        boolean [] boo = new boolean [32];
        Arrays.fill(boo, false);
        for(int i=a; i<=b; i++) {
            boo[i] = true;
        }
        int ans = count(boo);
        System.out.println(ans);
    }
    
    static int count(boolean[]boo) {
        int ans = 0;
        final int[] ARRAY = {23, 24, 25};
        for(int i=0; i<ARRAY.length; i++) {
            if(!boo[ARRAY[i]]) ans++;
        }
        return ans;
    }

}