#include <stdio.h>

 #include <string.h>

 #include <iostream>

 #include <algorithm>

 #include <stdlib.h>

 #include <vector>

 #include <queue>

 #include <stack>

 #define loop(s,i,n) for(i = s;i < n;i++)

 #define cl(a,b) memset(a,b,sizeof(a))

 using namespace std;

 int map[][];

 int r,c,n;

 struct node

 {

     int x,y;

 }p[];

 int cmp( struct node a, struct node b)

 {

     if(a.x == b.x)

     return a.y < b.y;

     return a.x < b.x;

 }

 int judge(int x,int y)

 {

     if(x >=  && x <= r && y >= &&y <= c)

     return ;

     return ;

 }

 int find(struct node tmp,int dx,int dy)

 {

     int ans = ;

     int leap =;

     while(judge(tmp.x+dx,tmp.y+dy))

     {

         if(map[tmp.x+dx][tmp.y+dy])

         {

             tmp.x+= dx,tmp.y += dy;

             ans++;

         }

         else

         {

             leap = ;

             break;

         }

     }

     if(leap)

     return ans;

     return ;

 }

 int main()

 {

     while(~scanf("%d %d",&r,&c))

     {

         int i,j;

         scanf("%d",&n);

         cl(map,);

         for(i = ;i <= n;i++)

         scanf("%d %d",&p[i].x,&p[i].y),map[p[i].x][p[i].y] = ;

         sort(p+,p+n+,cmp);

         int ans = ;

         for(i = ;i <= n;i++)

         {

             for(j = i+;j <= n;j++)

             {

                 int dx,dy;

                 dx = p[j].x-p[i].x;

                 dy = p[j].y-p[i].y;

                 struct node tmp;

                 tmp = p[j];

                 if(judge(p[i].x-dx,p[i].y-dy))

                 continue;

                 int cnt = find(tmp,dx,dy);

                 if(ans < cnt)

                 ans = cnt;

             }

         }

         if(ans < )

         puts("");

         else

         printf("%d\n",ans);

     }

     return ;

 }