def down_up(n):
    if n == 0:
        print n
    else:
        print n
        down_up(n-1)
        print(n)

def down_up_2(n):
    for i in range(n, -1, -1):
        print i
    for i in range(1,n+1):
        print i
        
def int2string(n):
    if n == 0:
        return '0'
    elif n > 0:
        return '+' * n
    else:
        return '-' * abs(n)