from bisect import bisect

# 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, input().split())
WH = []
for i in range(Q):
    WH.append(list(map(int,input().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))