from itertools import product
a =[0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19]

# [int(x) for x in input().split()][:2]

c= [0,1]
#  [int(x) for x in input().split()][:2]
arr = list(product(a,c))
for i in arr:
    print(i,end=' ')