N, M = map(int, input().split())
A = list(map(int, input().split())) + [1 << 60]

s = A[0]
l = 1
ans = []
for i in range(1, M + 1):
    if s + l == A[i]:
        l += 1
    else:
        ans.append((s, l))
        s = A[i]
        l = 1

print(len(ans))
for s, l in ans:
    print(s, l)