#include<iostream>
using namespace std;
#include<cstdio>
#include<cstring>
#include<cstdlib>
typedef short hd;
bool p[101][101],flag[101][101];
hd N,M;
hd dfs(hd x,hd y){
    flag[x][y]=1;
    hd ans=1;
    if(x+1<N&&!flag[x+1][y]&&p[x+1][y])ans+=dfs(x+1,y);
    if(x-1&&!flag[x-1][y]&&p[x-1][y])ans+=dfs(x-1,y);
    if(y+1<M&&!flag[x][y+1]&&p[x][y+1])ans+=dfs(x,y+1);
    if(y-1&&!flag[x][y-1]&&p[x][y-1])ans+=dfs(x,y-1);
    return ans;
}
int main(){
    freopen("lake.in","r",stdin),freopen("lake.out","w",stdout);
    hd i,j,K,ans=0,R,C;
    scanf("%hd%hd%hd",&N,&M,&K);
    ++N,++M;
    for(i=0;i<K;++i){
        scanf("%hd%hd",&R,&C);
        p[R][C]=1;
    }
    for(i=1;i<N;++i)
        for(j=1;j<M;++j)
            if(!flag[i][j]&&p[i][j])
                ans=max(dfs(i,j),ans);
    printf("%hd",ans);
}