from bisect import bisect
from sys import stdin

def solve(N, A):
    INF = 10**5

    dp = [INF]*(N+1)
    dp[0] = -1
    for a in A:
        idx = bisect(dp, a-1)
        dp[idx] = min(a, dp[idx])
    return max(i for i in range(N+1) if dp[i] < INF)

def main():
    readline = stdin.readline

    N,M,Q = map(int, readline().split())
    WH = []
    for _ in range(Q):
        WH.append(list(map(int,readline().split())))
    WH = sorted(WH,key=lambda x:(x[0],-x[1]))
    H = []
    for _,h in WH:
        H.append(h)

    print(solve(N,H))

main()