n,m,q = map(int,input().split())
dp = [[0] * (m+1) for _ in range(n+1)]
for i in range(q):
    a,b = map(int,input().split())
    dp[a][b] = 1
min_ = 0
for i in range(1,n+1):
    flg = True
    for j in range(1,m+1):
        if min_ < j:
            if dp[i][j] == 1:
                if flg:
                    dp[i][j] += max(dp[i-1][j],dp[i][j-1])
                    min_ = j
                    flg = False
                else:
                    dp[i][j] = max(dp[i-1][j],dp[i][j-1])
                continue
        dp[i][j] = max(dp[i-1][j],dp[i][j-1])
        
#         for _ in dp:
#             print(_)
#         print(i,j)

print(dp[-1][-1])