#include <bits/stdc++.h>
//eolibraries
#define lnf 3999999999999999999
#define inf 999999999
#define fi first
#define se second
#define pb push_back
#define all(c) (c).begin(),(c).end()
#define sz(c) (int)(c).size()
#define make_unique(a) sort(all(a)),a.erase(unique(all(a)),a.end());
#define rep(i,n) for(int i=0;i<n;i++)
#define drep(i,n) for(int i=n-1;i>=0;i--)
#define crep(i,x,n) for(int i=x;i<n;i++)
#define vec(...) vector<__VA_ARGS__>
#define _3ioVv0Q ios_base::sync_with_stdio(false),cin.tie(0),cout.tie(0)
//eodefine
using namespace std;
typedef long long i64;
typedef long double ld;
using pii=pair<int,int>;
using tpii=pair<int,pii>;
using vi=vec(i64);
const int mxn=12000;
int min(int o,int w){
	if(o<w) return o;
	return w;
}
int main(){
_3ioVv0Q;
	int n,m,q;
	cin>>n>>m>>q;
	vec(vi) rbts(n);
	rep(_,q){
		int u,v;
		cin>>u>>v;
		u--,v--;
		rbts[u].pb(v);
	}
	rep(i,n){
		sort(all(rbts[i]));
	}
	vec(vi) dp(n,vi(n+2,inf));
	rep(i,n){
		if(i) dp[i]=dp[i-1];
		if(sz(rbts[i])){
			int v=rbts[i][0];
			dp[i][1]=min(dp[i][1],v);
		}
		if(i){
			rep(j,n+1){
				int v=dp[i-1][j];
				if(v==inf) continue;
				auto it=upper_bound(all(rbts[i]),v);
				if(it==rbts[i].end()) continue;
				dp[i][j+1]=min(dp[i][j+1],*it);	
			}
		}
	}
	drep(j,n+1){
		if(dp[n-1][j]!=inf){
			cout<<j<<"\n";
			break;
		}
	}
//	
	return 0;
}