N, M = (int(x) for x in input().split())
A=list(map(int, input().split()))
ans=[]
ele=[A[0], 1]
for i in range(1, len(A)):
    if A[i]-A[i-1] == 1:
        ele[1] += 1
    else:
        ans.append(ele)
        ele = [A[i], 1]

if ele != []:
    ans.append(ele)

print(len(ans))
for S, L in ans:
    print(S, L)