import sys
input = sys.stdin.readline
N, M = map(int, input().split())
A = list(map(int, input().split()))
ans = []
for a in A:
    if len(ans)==0 or ans[-1][0]+ans[-1][1]!=a:
        ans.append([a, 1])
    else:
        ans[-1][1] += 1
print(len(ans))
for a in ans:
    print(*a)