import sys
input = sys.stdin.readline
from bisect import *

N, M, Q = map(int, input().split())
ab = [tuple(map(int, input().split())) for _ in range(Q)]
ab.sort(key=lambda t: (t[0], -t[1]))
dp = [10**18]*(N+1)
dp[0] = 0

for _, b in ab:
    dp[bisect_left(dp, b)] = b

print(bisect_left(dp, 10**18)-1)