#include <bits/stdc++.h>
using namespace std;
/*
#if __has_include(<boost/multiprecision/cpp_int.hpp>)
	#include <boost/multiprecision/cpp_int.hpp>
	#include <boost/multiprecision/cpp_dec_float.hpp>
	using bll = boost::multiprecision::cpp_int;
	using bdouble = boost::multiprecision::number<boost::multiprecision::cpp_dec_float<100>>;
	using namespace boost::multiprecision;
#endif
*/
#ifdef LOCAL_TEST
	#define BOOST_STACKTRACE_USE_ADDR2LINE
	#define BOOST_STACKTRACE_ADDR2LINE_LOCATION /usr/local/opt/binutils/bin/addr2line
	#define _GNU_SOURCE 1
	#include <boost/stacktrace.hpp>
	namespace std {
		template<typename T> class dvector : public std::vector<T> {
		public:
			dvector() : std::vector<T>() {}
			explicit dvector(size_t n, const T& value = T()) : std::vector<T>(n, value) {}
			dvector(const std::vector<T>& v) : std::vector<T>(v) {}
			dvector(const std::initializer_list<T> il) : std::vector<T>(il) {}
			dvector(const std::string::iterator first, const std::string::iterator last) : std::vector<T>(first, last) {}
			dvector(const typename std::vector<T>::iterator first, const typename std::vector<T>::iterator last) : std::vector<T>(first, last) {}
			dvector(const typename std::vector<T>::reverse_iterator first, const typename std::vector<T>::reverse_iterator last) : std::vector<T>(first, last) {}
			dvector(const typename std::vector<T>::const_iterator first, const typename std::vector<T>::const_iterator last) : std::vector<T>(first, last) {}
			dvector(const typename std::vector<T>::const_reverse_iterator first, const typename std::vector<T>::const_reverse_iterator last) : std::vector<T>(first, last) {}
			T& operator[](size_t n) {
				try { return this->at(n); } catch (const std::exception& e) { std::cerr << boost::stacktrace::stacktrace() << '\n'; return this->at(n); }
			}
			const T& operator[](size_t n) const {
				try { return this->at(n); } catch (const std::exception& e) { std::cerr << boost::stacktrace::stacktrace() << '\n'; return this->at(n); }
			}
		};
	}
	class dbool {
	private:
		bool boolvalue;
	public:
		dbool() : boolvalue(false) {}
		dbool(bool b) : boolvalue(b) {}
		operator bool&() { return boolvalue; }
		operator const bool&() const { return boolvalue; }
	};
	#define vector dvector
	#define bool dbool
	class SIGFPE_exception : std::exception {};
	class SIGSEGV_exception : std::exception {};
	void catch_SIGFPE([[maybe_unused]] int e) { std::cerr << boost::stacktrace::stacktrace() << '\n'; throw SIGFPE_exception(); }
	void catch_SIGSEGV([[maybe_unused]] int e) { std::cerr << boost::stacktrace::stacktrace() << '\n'; throw SIGSEGV_exception(); }
	signed convertedmain();
	signed main() { signal(SIGFPE, catch_SIGFPE); signal(SIGSEGV, catch_SIGSEGV); return convertedmain(); }
	#define main() convertedmain()
#endif
#ifdef LOCAL_DEV
	template<typename T1, typename T2> std::ostream& operator<<(std::ostream& s, const std::pair<T1, T2>& p) {
		return s << "(" << p.first << ", " << p.second << ")"; }
	template <typename T, size_t N> std::ostream& operator<<(std::ostream& s, const std::array<T, N>& a) {
		s << "{ "; for (size_t i = 0; i < N; ++i){ s << a[i] << "\t"; } s << "}"; return s; }
	template<typename T> std::ostream& operator<<(std::ostream& s, const std::set<T>& se) {
		s << "{ "; for (auto itr = se.begin(); itr != se.end(); ++itr){ s << (*itr) << "\t"; } s << "}"; return s; }
	template<typename T> std::ostream& operator<<(std::ostream& s, const std::multiset<T>& se) {
		s << "{ "; for (auto itr = se.begin(); itr != se.end(); ++itr){ s << (*itr) << "\t"; } s << "}"; return s; }
	template<typename T1, typename T2> std::ostream& operator<<(std::ostream& s, const std::map<T1, T2>& m) {
		s << "{\n"; for (auto itr = m.begin(); itr != m.end(); ++itr){ s << "\t" << (*itr).first << " : " << (*itr).second << "\n"; } s << "}"; return s; }
	template<typename T> std::ostream& operator<<(std::ostream& s, const std::deque<T>& v) {
		for (size_t i = 0; i < v.size(); ++i){ s << v[i]; if (i < v.size() - 1) s << "\t"; } return s; }
	template<typename T> std::ostream& operator<<(std::ostream& s, const std::vector<T>& v) {
		for (size_t i = 0; i < v.size(); ++i){ s << v[i]; if (i < v.size() - 1) s << "\t"; } return s; }
	template<typename T> std::ostream& operator<<(std::ostream& s, const std::vector<std::vector<T>>& vv) {
		s << "\\\n"; for (size_t i = 0; i < vv.size(); ++i){ s << vv[i] << "\n"; } return s; }
	void debug_impl() { std::cerr << '\n'; }
	template<typename Head, typename... Tail> void debug_impl(Head head, Tail... tail) { std::cerr << " " << head << (sizeof...(tail) ? "," : ""); debug_impl(tail...); }
	#define debug(...) do { std::cerr << "(" << #__VA_ARGS__ << ") ="; debug_impl(__VA_ARGS__); } while (false)
#else
	#define debug(...) do {} while (false)
#endif
//#define int long long
using ll = long long;
//constexpr int INF = (ll)1e9 + 7;//INT_MAX=(1<<31)-1=2147483647
constexpr ll INF = (ll)1e18;//(1LL<<63)-1=9223372036854775807
constexpr ll MOD = (ll)1e9 + 7;
constexpr double EPS = 1e-9;
constexpr ll dx[4] = {1, 0, -1, 0};
constexpr ll dy[4] = {0, 1, 0, -1};
constexpr ll dx8[8] = {1, 0, -1, 0, 1, 1, -1, -1};
constexpr ll dy8[8] = {0, 1, 0, -1, 1, -1, 1, -1};
#define rep(i, n)   for(ll i=0, i##_length=(n); i< i##_length; ++i)
#define repeq(i, n) for(ll i=1, i##_length=(n); i<=i##_length; ++i)
#define rrep(i, n)   for(ll i=(n)-1; i>=0; --i)
#define rrepeq(i, n) for(ll i=(n)  ; i>=1; --i)
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
void p() { std::cout << '\n'; }
template<typename Head, typename... Tail> void p(Head head, Tail... tail) { std::cout << head << (sizeof...(tail) ? " " : ""); p(tail...); }
template<typename T> inline void pv(std::vector<T>& v) { for(ll i=0, N=v.size(); i<N; i++) std::cout << v[i] << " \n"[i==N-1]; }
template<typename T> inline bool chmax(T& a, T b) { return a < b && (a = b, true); }
template<typename T> inline bool chmin(T& a, T b) { return a > b && (a = b, true); }
template<typename T> inline void uniq(std::vector<T>& v) { v.erase(std::unique(v.begin(), v.end()), v.end()); }

/*-----8<-----template-----8<-----*/

struct RangeSet{
	vector<vector<ll>> data;
	vector<ll> x;
	ll siz_x = 1;
	RangeSet(vector<pair<ll,ll>> a){
		sort(a.begin(), a.end());
		if(a.size()) x.push_back(a[0].first);
		for(auto& i : a) if(x.back() != i.first) x.push_back(i.first);
		while((ll)x.size() > siz_x) siz_x *= 2;
		while((ll)x.size() < siz_x) x.push_back(INF);
		data.resize(siz_x * 2);
		ll at = 0;
		for(auto& i : a){
			if(x[at] != i.first) at++;
			data[siz_x + at].push_back(i.second);
		}
		for(ll i = siz_x; --i; ){
			data[i].resize(data[i * 2].size() + data[i * 2 + 1].size());
			merge(data[i * 2].begin(), data[i * 2].end(), data[i * 2 + 1].begin(), data[i * 2 + 1].end(), data[i].begin());
		}
	}
	// クエリ [x1, x2) × [y1, y2) の長方形区域の和を返す
	ll query(ll x1, ll x2, ll y1, ll y2) const {
		ll l = lower_bound(x.begin(), x.end(), x1) - x.begin(), r = lower_bound(x.begin(), x.end(), x2) - x.begin();
		l += siz_x; r += siz_x;
		ll ans = 0;
		for(; l < r; l /= 2, r /= 2){
			if(l & 1){
				ans += lower_bound(data[l].begin(), data[l].end(), y2) - lower_bound(data[l].begin(), data[l].end(), y1);
				l++;
			}
			if(r & 1){
				r--;
				ans += lower_bound(data[r].begin(), data[r].end(), y2) - lower_bound(data[r].begin(), data[r].end(), y1);
			}
		}
		return ans;
	}
};

/*-----8<-----library-----8<-----*/

constexpr ll H_MAX = 3*1e5;
constexpr ll W_MAX = 3*1e5;

ll H, W, M;


void solve() {
	cin >> H >> W >> M;
	//h = vector<ll>(M);
	//w = vector<ll>(M);
	vector<pair<ll,ll>> a(M);
	set<pair<ll,ll>> s;
	rep(i, M) { cin >> a[i].first >> a[i].second; 
		a[i].first--;a[i].second--;
		s.insert(a[i]);
	}


	RangeSet seg(a);
	vector<pair<ll,ll>> h(H);
	vector<pair<ll,ll>> w(W);
	rep(i,H)h[i]={seg.query(i,i+1, 0,W),i};
	rep(j,W)w[j]={seg.query(0,H, j,j+1),j};
	sort(rall(h));
	sort(rall(w));

	vector<ll> hset,wset;
	rep(i,H)if(h[i].first==h[0].first)hset.push_back(h[i].second); else break;
	rep(j,W)if(w[j].first==w[0].first)wset.push_back(w[j].second); else break;

	ll ans = h[0].first + w[0].first;
	debug(s);
	debug(h);
	debug(w);
	debug(hset);
	debug(wset);
	debug(ans);
	rep(i,hset.size())rep(j,wset.size()){
		if(s.find({hset[i], wset[j]}) == s.end()){
			debug(111,hset[i], wset[j]);
			p(ans);return;
		}
	}
	
	cout << ans-1 << '\n';
}

// https://atcoder.jp/contests/abc176/tasks/abc176_e
signed main() {
	std::cin.tie(nullptr);
	std::ios::sync_with_stdio(false);
	//ll Q; cin >> Q; while(Q--)solve();
	solve();
	return 0;
}


Measured memory_bytes: 131948