#include<iostream>
#include<cstdio>
#include<queue>
using namespace std;
int n,m,k;
int ans=0;
int dt[101][101];
int d[5]={0,1,0,-1};
int b[5]={1,0,-1,0};
queue<int> q;
queue<int> p;
void bfs(int i,int j)
{
	int tot=1;
	p.push(i);
	q.push(j);
	dt[i][j]=0;

	while( !q.empty()  && !p.empty() )
	{
		int k=p.front(),h=q.front();
		dt[k][h]=0;
		for(int i=0;i<=3;i++)
		{
			if(  k+b[i] >= 0  && k+b[i] <= n &&  h+d[i] >= 0  && h+d[i] <= m )
  	if(dt[k+b[i]][h+d[i]])
			{
					p.push(k+b[i]);
					q.push(h+d[i]);
					dt[k+b[i]][h+d[i]]=0;
					tot++;
			}
  }
  q.pop();
		p.pop();
	}
	if(ans<tot) ans=tot;
}

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

	cin>>n>>m>>k;
	for(int i=1;i<=k;i++)
	{
		int aa,bb;
		cin>>aa>>bb;
		dt[aa][bb]=1;
	}

	for(int i=1;i<=n;i++)
	{
		for(int j=1;j<=m;j++)
		{
			if(dt[i][j])
			{
				bfs(i,j);
			}
		}
	}

	cout<<ans;

}