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

for i in range(1,n+1):
    for j in range(1,m+1):
        dp[i][j] += max(dp[i-1][j],dp[i][j-1])

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