#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef pair<ll, ll> p_ll;

template<class T>
void debug(T itr1, T itr2) { auto now = itr1; while(now<itr2) { cout << *now << " "; now++; } cout << endl; }
#define repr(i,from,to) for (ll i=(ll)from; i<(ll)to; i++)
#define all(vec) vec.begin(), vec.end()
#define rep(i,N) repr(i,0,N)
#define per(i,N) for (ll i=(ll)N-1; i>=0; i--)
#define popcount __builtin_popcount

const ll LLINF = pow(2,61)-1;
const ll INF = pow(2,30)-1;

ll gcd(ll a, ll b) { if (a<b) swap(a,b); return b==0 ? a : gcd(b, a%b); }
ll lcm(ll a, ll b) { return a/gcd(a,b)*b; }

void chmax(ll &x, ll y) { x = max(x, y); }

int main() {
  ll N, M, Q; cin >> N >> M >> Q;
  vector<ll> a(Q), b(Q); rep(i,Q) { cin >> a[i] >> b[i]; a[i]--; b[i]--; }
  vector<vector<ll>> ok(N, vector<ll>(M));
  rep(i,Q) ok[a[i]][b[i]]++;

  assert(1<=N && N<=1000);
  assert(1<=M && M<=1000);
  assert(1<=Q && Q<=N*M);
  rep(i,N) rep(j,M) assert(ok[i][j]<=1);

  vector<vector<ll>> dp(N+1, vector<ll>(M+1));
  repr(i,1,N+1) repr(j,1,M+1) {
    chmax(dp[i][j], dp[i-1][j]);
    chmax(dp[i][j], dp[i][j-1]);
    if (ok[i-1][j-1]) chmax(dp[i][j], dp[i-1][j-1]+1);
  }

  // rep(i,N+1) debug(all(dp[i]));
  cout << dp[N][M] << endl;
  return 0;
}