N,M,Q = map(int,input().split())
lsAB = [set() for i in range(N+1)]
for i in range(Q):
    a,b = map(int,input().split())
    lsAB[a].add(b)
dp = [[0]*(M+1) for i in range(N+1)]

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