import sys,random
from collections import deque
from heapq import heappush,heappop

input = lambda :sys.stdin.readline().rstrip()
mi = lambda :map(int,input().split())
li = lambda :list(mi())

N,M,Q = mi()

pair = [[] for i in range(N+1)]
for _ in range(Q):
    a,b = mi()
    pair[a].append(b)

INF = 10**9
dp = [0 for w in range(M+1)]
for i in range(N):
    ndp = [x for x in dp]
    for w in pair[i+1]:
        ndp[w] = max(ndp[w],dp[w-1]+1)
    dp = ndp
    for w in range(1,M+1):
        dp[w] = max(dp[w],dp[w-1])

print(max(dp))