N, M = (int(x) for x in input().split())
A = [int(x) for x in input().split()]

result = []
for a in A:
    if result and result[-1][0] + result[-1][1] == a:
        result[-1][1] += 1
    else:
        result.append([a, 1])

print(len(result))
for r in result:
    print(*r)