import sys
input = sys.stdin.readline

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

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 par[i][j]:
            dp[i][j] = dp[i-1][j-1]+1
        else:
            dp[i][j] = max(dp[i-1][j],dp[i][j-1])
print(dp[-1][-1])