par-primo spoj

while True:
    m,n = map(int,raw_input().split())
    if m == n == 0: break
    pp = 0
    for i in range(m,n+1):
        cont = 0
        for j in range(1,i+1):
            if i % j == 0: cont+=1
        if cont % 2 == 0: pp+=1
    print pp