#include <stdio.h>

#define NMAX 100
#define MMAX 100

int f[NMAX+2][MMAX+2];

int t(int y,int x){
	int num=1;

	f[y][x]=0;
	if(f[y-1][x])num+=t(y-1,x);
	if(f[y+1][x])num+=t(y+1,x);
	if(f[y][x-1])num+=t(y,x-1);
	if(f[y][x+1])num+=t(y,x+1);
	return num;
}

int main(){
	int n,m,k;
	int r,c;
	int tmp,max;
	int i,j;

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

	scanf("%d%d%d",&n,&m,&k);
	getchar();
	for(i=0;i<k;i++){
		scanf("%d%d",&r,&c);
		getchar();
		f[r][c]=1;
	}

	max=1;
	for(i=1;i<=n;i++){
		for(j=1;j<=m;j++){
			if(f[i][j]){
				tmp=t(i,j);
				if(tmp>max)max=tmp;
			}
		}
	}
	printf("%d",max);
	return 0;
}