#include <iostream>
using namespace std;

int dx[4] = {0, -1, 1, 0};
int dy[4] = {-1, 0, 0, 1};

int arr[101][101];
int n, m;

int change(int y, int x) {
    arr[y][x] = 0;
    int size = 1;

    for (int k = 0; k < 4; k++) {
        int ny = y + dy[k];
        int nx = x + dx[k];

        if (ny >= 0 && ny < n && nx >= 0 && nx < m && arr[ny][nx] == 1) {
            size += change(ny, nx);
        }
    }
    return size;
}

int main() {
    int k;
    cin >> n >> m >> k;

    for (int i = 0; i < k; i++) {
        int a, b;
        cin >> a >> b;
        arr[a-1][b-1] = 1; 
    }

    int cnt = 0;

    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            if (arr[i][j] == 1) {
                int cur = change(i, j);
                cnt = max(cnt, cur);
            }
        }
    }

    cout << cnt;
}