#include<cstdio>
#include<iostream>
using namespace std;

int n,m,k,map[101][101],vis[101][101];
int ans,res;

void dfs(int x,int y) {
    if(x<1 || x>n || y<1 || y>m || vis[x][y]) return;
    if(map[x][y]) res++,vis[x][y]=1;
    if(map[x+1][y]) dfs(x+1,y);
    if(map[x][y+1]) dfs(x,y+1);
    if(map[x-1][y]) dfs(x-1,y);
    if(map[x][y-1]) dfs(x,y-1);
}

int main() {
    freopen("lake.in","r",stdin);  
    freopen("lake.out","w",stdout);  
    cin>>n>>m>>k;
    for(int i=1;i<=k;i++){
        int a,b;
        cin>>a>>b;
        map[a][b]=1;
    }
    for(int i=1;i<=n;i++)
        for(int j=1;j<=m;j++){
            res=0;
            if(map[i][j]) dfs(i,j);
            if(res>ans) ans=res;
        }
    cout<<ans;
    fclose(stdin);
    fclose(stdout);
    return 0;
}