n,m,q = map(int,input().split())
par = [[0]*(m+1) for i in range(n+1)]
for i in range(q):
    a,b = map(int,input().split())
    par[a][b] =  1

dp = [[0]*(m+2) for i in range(n+2)]
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])
        if par[i][j]:
            dp[i][j] = max(dp[i][j],dp[i-1][j-1]+1)
        
print(dp[n][m])