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

N, M, Q = map(int, input().split())
ok = [[False]*(M+1) for _ in range(N+1)]

for _ in range(Q):
    a, b = map(int, input().split())
    ok[a][b] = True

dp = [[0]*(M+1) for _ in range(N+1)]

for i in range(1, N+1):
    for j in range(1, M+1):
        dp[i][j] = max(dp[i][j], dp[i-1][j], dp[i][j-1], dp[i-1][j-1])
        
        if ok[i][j]:
            dp[i][j] = max(dp[i][j], dp[i-1][j-1]+1)

print(dp[N][M])