n,m = map(int ,input().split() )
A=[int(x) for x in input().split()]
A.append(n+10)#番兵
ans=[]
top=A[0]
cnt=1
for i in range(m):
	if A[i+1]-A[i]>1:
		ans.append((top,cnt))
		cnt=1
		top=A[i+1]
	else:
		cnt+=1
print(len(ans))
for a in ans:
	print(*a)