#include <iostream>
#include <cstdio>
#include <fstream>
#include <algorithm>
#include <vector>
#include <string.h>
#include <queue>
#define INF 99999999999
using namespace std;
typedef long long lld;

    lld eabs(lld num)
    {
        if (num < 0) return -num;
        return num;
    }
struct Point
{
    lld x, y;

    void SetValues(lld nx, lld ny)
    {
        x = nx;
        y = ny;
    }

    bool operator<(const Point& other)const
    {
        if (y != other.y) return (y < other.y);
        return (x < other.x);
    }

    lld operator/(const Point& other)const
    {
        lld ret = 0;

        if (eabs(x-other.x) < eabs(y-other.y))
        {
            ret = eabs(x-other.x) + (eabs(y-other.y) - eabs(x - other.x));
        }

        else
        {
            ret = eabs(y-other.y) + (eabs(x-other.x) - eabs(y - other.y));
        }

        return ret;
    }

};

lld MN(lld a, lld b)
{
    if (a < b) return a;
    return b;
}

lld n, m, k;
vector<Point> pts;

bool SHbyX(Point a, Point b)
{
    if (a.x != b.x) return (a.x < b.x);
    return (a.y < b.y);
}
void Sleep()
{
    for (lld i=0;i<500000000;i++)
    {

    }
}

lld Get(lld from, lld to)
{
    //cout<<"Tursim ot "<<from<<" do "<<to<<endl;
    if (from == to) return INF;
    if (from+1 == to) return pts[from]/pts[to];

    //Sleep();

    lld i, j;
    lld ret;
    lld mid = (from+to)/2;
    vector<Point> tmp;
    Point hpr;

    ret = MN(Get(from, mid), Get(mid+1, to));

    //cout<<"Minimalnoto ot "<<from<<" do "<<mid<<" vs "<<mid+1<<" do "<<to<<" e "<<ret<<endl;

    for (i= from; i<=to; i++)
    {
        if (eabs(pts[i].y - pts[mid].y) >= ret) continue;

        //cout<<"Dobavqme ("<<pts[i].x<<","<<pts[i].y<<")"<<endl;

        tmp.push_back(pts[i]);
    }

    sort(tmp.begin(), tmp.end(), SHbyX);

    for (i=0; i<tmp.size(); i++)
    {
        for (j=i+1; j<tmp.size(); j++)
        {
           // cout<<"Probvame ot ("<<tmp[i].x<<","<<tmp[i].y<<")"<<" do ("<<tmp[j].x<<","<<tmp[j].y<<")"<<", koeto e "<<tmp[i]/tmp[j]<<endl;
            if (tmp[i]/tmp[j] >= ret) break;

           // cout<<"Novo razstoqnie ot ("<<tmp[i].x<<","<<tmp[i].y<<")"<<" do ("<<tmp[j].x<<","<<tmp[j].y<<")"<<", koeto e "<<tmp[i]/tmp[j]<<endl;

            ret = MN(ret, tmp[i]/tmp[j]);
        }
    }

    //cout<<"Ot "<<from<<" do "<<to<<" e "<<ret<<endl;
    return ret;
}

lld Stupid()
{
    lld ans = INF;
    lld i, j;

    for (i=0;i<pts.size();i++)
    {
        for (j=i+1;j<pts.size();j++)
        {
            ans = MN(ans, pts[i]/pts[j]);
        }
    }

    return ans;
}



int main ()
{
    freopen("robot.in", "r", stdin);
    freopen("robot.out", "w", stdout);

    lld i, j, ii, jj, ind;
    lld a, b;
    Point h;

    scanf("%lld %lld %lld", &n, &m, &k);

    for (i=1;i<=k;i++)
    {
        scanf("%lld %lld", &a, &b);

        h.SetValues(a, b);
        pts.push_back(h);
    }

    /*for (i=0;i<pts.size();i++)
    {
        for (j=i+1;j<pts.size();j++)
        {
            printf("Razstoqnieto ot %lld do %lld e %lld\n", i, j, pts[i]&pts[j]);
        }
    }*/



    //return 0;
    sort(pts.begin(), pts.end());

    /*for (i=0; i<pts.size(); i++)
    {
        printf("%lld %lld\n", pts[i].x, pts[i].y);
    }*/

    lld ans, stp;
    ans = Get(0, pts.size()-1);
    //stp = Stupid();

    //cout<<stp<<endl;
    printf("%lld\n", ans);
}