# Enter your code here. Read input from STDIN. Print output to STDOUT
import math as m
import sys

def lps(n):
    ref=m.floor(m.sqrt(n))
    result=1
    temp=[]

    for i in range(2,ref+1):
        #lets find out the greatest prime no less than ref
        
        for j in range(2,i):
            if i%j==0:
                break
        else:#this else is for FOR loop
            temp.append(i)
            #print("lps appended",temp)
    result=max(temp)
    return result # returns lps value for input as n

def ups(n):
    ref=m.ceil(m.sqrt(n))
    result=1
    temp=[]

    for i in range(ref,30):
        #lets find out the smallest prime no greater than ref
        for j in range(2,i):
            if i%j==0:
                break
        else:
            temp.append(i)
            #print("ups appended",temp)
    result=min(temp)
    return result

#main function:
arr=list(map(int,input().split()))
L=arr[0]
R=arr[1]
if (L not in range(4,pow(10,18))) or (R not in range(4,pow(10,18)))or((R-L)>pow(10,16)):
    sys.exit()

ans_lst=[]
try:
    for i in range(L,R+1):
        lps_val=lps(i)
        #print("debug lps val=",lps_val)
        ups_val=ups(i)
        #print("debug ups val=",ups_val)
        if (i%lps_val==0 and i%ups_val!=0) or (i%ups_val==0 and i%lps_val!=0):
            ans_lst.append(i)
    print(sum(ans_lst)%1004535809)
    #print("debug ans_list : ",ans_lst)
except ZeroDivisionError:
    print("Unexpected glitch")
    sys.exit()