#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, srt, end) for (long long i = (srt); i < (long long)(end); i++)
// Ref: https://qiita.com/ysuzuki19/items/d89057d65284ba1a16ac
#define dump(var)  do{std::cerr << #var << " : ";view(var);}while(0)
template<typename T> void view(T e){std::cerr << e << "\n";}
template<typename T> void view(const std::vector<T>& v){for(const auto& e : v){ std::cerr << e << " "; } std::cerr << "\n";}
template<typename T> void view(const std::vector<std::vector<T> >& vv){ std::cerr << "\n"; for(const auto& v : vv){ view(v); } }
template<typename T> void dump_cout(const T& v) { for(long long i = 0; i < v.size(); i++) std::cout << v[i] << (i == v.size()-1 ? "\n" : " "); }

#include <atcoder/segtree>
using namespace atcoder;
using S = ll;
S op(S a, S b) { return max(a, b); }
S e() { return 0; }

void solve() {
    ll n, m, q;
    cin >> n >> m >> q;
    vector<vector<ll>> G(n);
    rep(i, 0, q) {
        ll u, v;
        cin >> u >> v;
        u--; v--;
        G[u].push_back(v);
    }
    segtree<S, op, e> seg(m+10);
    rep(i, 0, n) {
        map<ll,ll> tmp;
        for(auto j : G[i]) {
            tmp[j] = max(tmp[j], seg.prod(0, j) + 1);
        }
        for(auto [f, s] : tmp) seg.set(f, max(s, seg.get(f)));
    }
    cout << seg.all_prod() << endl;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    solve();
    return 0;
}