N, M = map(int, input().split())
A = list(map(int, input().split()))

answer = [[A[0], 1]]

for i in range(M - 1):
    if A[i] + 1 == A[i + 1]:
        answer[-1][1] += 1
    else:
        answer.append([A[i + 1], 1])

print(len(answer))
print(*[f"{s} {l}" for s, l in answer], sep="\n")