189: 素数判定(python)

def prime(n):
    for i in range(2,n//2+1):
        if n%i==0:
            return False
    return True
def zone_prime(a,b):
    count=0
    for i in range(a,b+1):
        if prime(i):
            count=count+1
    print(count)
while True:
    try:
        a,b=map(int,input().split())
        if a > b:
            a, b = b, a
        zone_prime(a,b)
    except EOFError:
        break