N, K = map(int,input().split())
li = list(map(int,input().split()))
ans = []
count = 1
for i in range(K -1):
    if(li[i + 1] != li[i] + 1):
        ans.append((li[i - count + 1], count))
        count = 1
    else:
        count += 1
ans.append((li[K - count], count))
print(len(ans))
for a, b in ans:
    print(a, b)