#include<iostream>

#include<cstdio>

#include<cstring>

#include<string>

#include<cmath>

#include<algorithm>

using namespace std;

int k,a,b,f[][],tot;

void search(int x,int y)

{

    if(x==a&&y==b)

    {

        tot++;

        return;

    }

    if((x+<=a)&&f[x+][y]==)//往上找

    search(x+,y);

    if((y+<=b)&&f[x][y+]==)//往右找

    search(x,y+);

}

int main()

{

    cin>>a>>b>>k;

    for(int i=;i<=k;i++)

    {

        int x,y;

        cin>>x>>y;

        f[x][y]=;

    }

    search(,);

    cout<<tot;

    return ;

}