n, m, q = map(int, input().split())
C = [[0 for _ in range(m)] for _ in range(n)]
for _ in range(q):
    a, b = map(int, input().split())
    C[a - 1][b - 1] = 1

DP = [[0 for _ in range(m + 1)] for _ in range(n + 1)]
for i in range(1, n + 1):
    for j in range(1, m + 1):
        if C[i - 1][j - 1] == 1:
            DP[i][j] = DP[i - 1][j - 1] + 1
        else:
            DP[i][j] = max(DP[i - 1][j], DP[i][j - 1])
print(DP[n][m])