n,d,m = map(int,input().split())
nums = [int(x) for x in input().split()]
for i in range(m):
nums[i]=[nums[i],i+1]
nums.sort()
def check(x):
time = [0]*x
c = 0
ans = 0
for i in range(m):
if c == x:
c = 0
if time[c] >= nums[i][0]:
time[c]+=1
ans = max(ans,time[c]-nums[i][0])
else:
time[c]=nums[i][0]
c+=1
return ans <= d
lo = 1
hi = m
while lo < hi:
mid = (lo+hi)//2
if check(mid):
hi = mid
else:
lo = mid+1
print(lo)
final = [[] for i in range(10001)]
last = [0]*lo
c = 0
for i in range(m):
if c == lo:
c = 0
last[c] = max(last[c]+1,nums[i][0])
final[last[c]].append(nums[i][1])
c+=1
for i in range(1,n+1):
print(*(final[i]+[0]))
