
def is_prime2(q,k=100):
    q = abs(q)
    if q == 2: return True
    if q < 2 or q&1 == 0: return False
    for i in xrange(3,k):
        x,y = q,i
        while y:
            x, y =  y, x % y
        if x != 1: continue
        if pow(i, q-1, q) != 1:
            return False
    return True

while True:
    n = input()
    if (n == 0):
        break
    if (n < 19):
        print 13
    else:
        print "hoge"
        break
        tmp = int((n - 19) / 30)
        while tmp > 0:
            x = 30 * tmp + 19
            if (is_prime2(x) and is_prime2(x - 2) and is_prime2(x - 6) and is_prime2(x - 8)):
                print x
                break
            tmp -= 1