#include<iostream>
#define endl '\n'
using namespace std;
int s[20002][20002];
int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    long long n,m,k,br=0,j,a,b,i,h=0;
    cin>>n>>m>>k;
    if(n%2==0&& m%2==0){
    for(i=0;i<k;i++)
    {
        cin>>a>>b;

        if(a>n/2)a=n-a+1;
        if(b>m/2)b=m-b+1;
        s[a][b]=1;
    }
    for(i=1;i<=n/2;i++)
    {
        for(j=1;j<=m/2;j++)
        {
            if(s[i][j]==1)br++;
        }
    }
    cout<<br*4<<endl;return 0;}
    else if(n%2==0)
    {
    int z=0;
    for(i=0;i<k;i++)
    {
        cin>>a>>b;
        if(b==m/2+1)z=2;
        else {if(a>n/2)a=n-a+1;
        if(b>m/2+1)b=m-b+1;

        s[a][b]=1;}
    }
    for(i=1;i<=n/2;i++)
    {
        for(j=1;j<=m/2;j++)
        {
            if(s[i][j]==1)br++;
        }
    }
    cout<<br*4+z<<endl;return 0;
    }
    else if(m%2==0)
    {
        int z=0;
    for(i=0;i<k;i++)
    {
        cin>>a>>b;

        if(a>n/2+1)a=n-a+1;
        else {if(b>m/2)b=m-b+1;
        if(b==n/2+1)z=2;
        s[a][b]=1;}
    }
    for(i=1;i<=n/2;i++)
    {
        for(j=1;j<=m/2;j++)
        {
            if(s[i][j]==1)br++;
        }
    }
    cout<<br*4+z<<endl;return 0;

    }
    else
    {
        bool q=true;
        int z=0;
    for(i=0;i<k;i++)
    {
        cin>>a>>b;
        if(a==n/2+1&&b==m/2+1)h=3;
        if(a>n/2+1)a=n-a+1;
        if(b>m/2+1)b=m-b+1;

        if((b==n/2+1||a==n/2+1)&&q){br++;q=false;}
        s[a][b]=1;
    }
    for(i=1;i<=n/2;i++)
    {
        for(j=1;j<=m/2;j++)
        {
            if(s[i][j]==1)br++;
        }
    }
    cout<<br*4-h<<endl;return 0;
    }


    return 0;
}
/*
5 6 6
2 5
4 2
1 3
3 1
5 6
5 1
*/