#include<iostream>  
#include<cstdio>
#include<cmath>
#include<cstring>  
#include<algorithm>  
using namespace std; 
int n,m,k,mp[101][101],a1,a2,ma=0,sum;
void dfs(int x,int y){
	if(!mp[x][y])return;
	mp[x][y]=0;
	sum+=1;
	dfs(x+1,y);dfs(x,y+1);
	dfs(x-1,y);dfs(x,y-1);
	return;
}
int main(){ 
    freopen("lake.in","r",stdin);        
    freopen("lake.out","w",stdout);      
	cin>>n>>m>>k;
	for(int i=1;i<=k;++i){
		cin>>a1>>a2;
		mp[a1][a2]=1;
	}
	for(int i=1;i<=n;++i){
		for(int j=1;j<=m;++j){
			if(mp[i][j]){
				sum=0;
				dfs(i,j);
				ma=max(ma,sum);
			}
		}
	}
	cout<<ma;
    return 0;  
}