#include<bits/stdc++.h>
#include<atcoder/all>
using namespace std;
using namespace atcoder;
#define rep(i,n)for (int i = 0; i < int(n); ++i)
#define rrep(i,n)for (int i = int(n)-1; i >= 0; --i)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
template<class T> void chmax(T& a, const T& b) {a = max(a, b);}
template<class T> void chmin(T& a, const T& b) {a = min(a, b);}
using ll = long long;
using P = pair<int,int>;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;

int op(int x, int y) { return max(x, y); }
int e() { return -1001001001; }

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n, m, q;
    cin >> n >> m >> q;
    VI cnt1(n), cnt2(m);
    VI to1(n, -1), to2(m, -1);
    rep(_, q) {
        int a, b;
        cin >> a >> b;
        cnt1[a - 1]++;
        cnt2[b - 1]++;
        to1[a - 1] = b - 1;
        to2[b - 1] = a - 1;
    }
    vector<char> valid1(n, true), valid2(m, true);
    rep(i, n) if (cnt1[i] >= 2 || cnt1[i] == 1 && cnt2[to1[i]] >= 2) valid1[i] = false;
    rep(i, m) if (cnt2[i] >= 2 || cnt2[i] == 1 && cnt1[to2[i]] >= 2) valid2[i] = false;
    VI idx1(n), idx2(m);
    {
        int p1 = 0;
        rep(i, n) if (valid1[i]) idx1[i] = p1++;
        int p2 = 0;
        rep(i, m) if (valid2[i]) idx2[i] = p2++;
        VI nto1(p1), nto2(p2);
        rep(i, n) if (valid1[i]) nto1[i] = cnt1[i] == 0 ? -1 : idx2[to1[i]];
        rep(i, m) if (valid2[i]) nto2[i] = cnt2[i] == 0 ? -1 : idx1[to2[i]];
        n = p1, m = p2, to1 = nto1, to2 = nto2;
    }
    int base = n, add = 0;
    segtree<int, op, e> seg(n + m + 1);
    seg.set(base, 0);
    rep(i, n) {
        if (to1[i] != -1) {
            int j = to1[i];
            int x = seg.prod(base, base + j + 1) + 1;
            seg.set(base + j + 1, max(x, seg.get(base + j + 1)));
        } else {
            base--, add++;
        }
    }
    int ans = seg.prod(base, base + m + 1) + add;
    cout << ans << endl;
}