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

scenes = [[A[0]]]
for i in range(1, M):
    if A[i] == scenes[-1][-1] + 1:
        scenes[-1].append(A[i])
    else:
        scenes.append([A[i]])
    
print(len(scenes))
for s in scenes:
    print(s[0], len(s))