from bisect import bisect
from sys import stdin

def main():
    readline = stdin.readline
    # N: 数列の長さ
    # A[i]: a_i の値
    def solve(N, A):
        INF = 10**10

        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)

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

    print(solve(N,H))

main()