#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<queue>
using namespace std;
int n,m,t;
int map[210][210];
bool b[210][210];
int ans=0;
int num=0;
queue <int> qx,qy;

void bfs(int ,int );

int main()
{
	freopen("lake.in","r",stdin);
	freopen("lake.out","w",stdout);
	ios::sync_with_stdio(false);
	cin>>n>>m>>t;
	int x,y;
	memset(b,1,sizeof(b));
	for(int i=1;i<=n;i++)
	for(int j=1;j<=m;j++)
	b[i][j]=0;
	for(int i=1;i<=t;i++)
	{
		cin>>x>>y;
		map[x][y]=1;
	}
	for(int i=1;i<=n;i++)
	for(int j=1;j<=m;j++)
	if(map[i][j]&&!b[i][j])
	{
		num=0;
		bfs(i,j);
		if(num>ans)ans=num;
	}
	cout<<ans<<endl;
	return 0;
}
void bfs(int x,int y)
{
	qx.push(x);
	qy.push(y);
	b[x][y]=1;
	while(!qx.empty())
	{
		int xx=qx.front();
		int yy=qy.front();
		
		if(map[xx][yy+1]&&!b[xx][yy+1])
		{
			qx.push(xx);
			qy.push(yy+1);
			b[xx][yy+1]=1;
		}
		if(map[xx][yy-1]&&!b[xx][yy-1])
		{
			qx.push(xx);
			qy.push(yy-1);
			b[xx][yy-1]=1;
		}
		
		if(map[xx+1][yy]&&!b[xx+1][yy])
		{
			qx.push(xx+1);
			qy.push(yy);
			b[xx+1][yy]=1;
		}
		if(map[xx-1][yy]&&!b[xx-1][yy])
		{
			qx.push(xx-1);
			qy.push(yy);
			b[xx-1][yy]=1;
		}
		qx.pop();
		qy.pop();
		num++;
	}
}