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

ans = []
start = A[0]
pre = A[0]
for a in A[1:]:
    if pre+1 == a:
        pre += 1
    else:
        ans.append((start, pre-start+1))
        start = a
        pre = a
ans.append((start, pre-start+1))

print(len(ans))
for a, b in ans:
    print(a, b)