a,b=map(int,input().split())
c=list(map(int,input().split()))
strawberry=[[] for i in range(a)]
for i in range(a-1):
	for j in range(i+1,a):
		if c[i]==c[j]:
			strawberry[i].append(j)
			strawberry[j].append(i)
print(strawberry)