N, M = map(int, input().split())
A = list(map(int, input().split()))
i = 0
ans = []
while i < M:
    s = i
    while i < M - 1 and A[i] + 1 == A[i + 1]:
        i += 1
    ans.append((A[s], i - s + 1))
    i += 1
print(len(ans))
for row in ans:
    print(*row)