#include <bits/stdc++.h>
using namespace std;
#define f(i,k,n) for(int i=k; i<n; i++)
#define ll long long
const int inf = INT_MAX;

void solve()
{
    int n,m,k;
    cin>>n>>m>>k;
    vector<vector<int>> a;
    int x,y;
    f(i,0,k)
    {
        cin>>x>>y;
        a.push_back({x,y});
    }
    sort(a.begin(),a.end());
    int c=1;
    int asd=k-1;
    vector<int> w=a[0];
    while(a[asd][0]==a[k-1][0])
    {
        w=a[asd];
        asd--;
    } 
    //cout<<w[0]<<" "<<w[1]<<"\t"<<asd<<"\n";
    while(asd>=0)
    {
        if(a[asd][0]<w[0] && a[asd][1]>w[1]) 
        {
            vector<int> m=a[asd];
            while(asd>=1 && a[asd-1][0]<w[0] && a[asd-1][1]>w[1] && a[asd-1][0]==m[0]) asd--;
            //cout<<a[asd][0]<<" "<<a[asd][1]<<"\n";
            c++;   
            w=a[asd]; 
        }
        asd--; 
    } 
    cout<<c;
}

int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    int t=1;
    //cin>>t;
    while(t--)  solve();
    return 0;
}