#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
int n,m,k,f[101][101],a[10001],xi[4]={-1,0,0,1},yi[4]={0,-1,1,0},maxn;
void search(int x,int y)
{
	int i,xx,yy;
	for(i=0;i<4;++i)
	{
		xx=x+xi[i]; yy=y+yi[i];
		if(f[xx][yy])
		{
			f[xx][yy]=0;
			maxn+=1;
			search(xx,yy);
		}
	}
}
int main()
{
	freopen("lake.in","r",stdin);
	freopen("lake.out","w",stdout);
	int x,y,i,j,ans=0;
	cin>>n>>m>>k;
	memset(f,0,sizeof(f));
	for(i=1;i<=k;++i)
	{
		cin>>x>>y;
		f[x][y]=1;
	}
	for(i=1;i<=k;++i)
	  a[k]=1;
	for(i=1;i<=n;++i)
      for(j=1;j<=m;++j)
        if(f[i][j])
        {
        	f[i][j]=0;
        	maxn=1;
        	search(i,j);
        	ans=max(ans,maxn);
        }
    cout<<ans<<endl;
    fclose(stdin);
    fclose(stdout);
}