#include<bits/stdc++.h>
using namespace std;
//#pragma GCC optimize("Ofast")
//#pragma GCC optimize("unroll-loops")
//#pragma GCC target("avx2")

using ll = long long;
//using i128 = __int128_t;
#define endl "\n"
#define int long long
#define db cout << "db" << endl;
#define x first
#define y second
typedef pair<int, int> PII;
const int N = 1e5 + 10, M = 3010;
ll inf = 2e18;
int n, m, k;
int a[N], b[N], dis[M][M], ma[M][M], vis[M][M];
string s[M];
int dx[] = {1, -1, 0, 0};
int dy[] = {0, 0, 1, -1};

void bfs(int x, int y) {
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < m; j++) {
			dis[i][j] = inf;
		}
	}
	dis[x][y] = 0;
	queue<PII> q;
	q.push({x, y});
	while (q.size()) {
		int x1 = q.front().x, y1 = q.front().y;
		q.pop();

		if (vis[x1][y1]) {
			continue;
		}
		vis[x1][y1] = 1;
		for (int i = 0; i < 4; i++) {
			int x2 = x1 + dx[i], y2 = y1 + dy[i];
			if (x2 < 0 || x2 >= n || y2 < 0 || y2 >= m || s[x2][y2] == '#') {
				continue;
			} else if (ma[x2][y2] && dis[x1][y1] < k - ma[x2][y2]) {
				dis[x2][y2] = min(dis[x2][y2], k - ma[x2][y2] + 1);
				q.push({x2, y2});
			} else if (dis[x2][y2] > dis[x1][y1] + 1){
				dis[x2][y2] = dis[x1][y1] + 1;
				q.push({x2, y2});
			}
		}

	}
}
void solve() {
    
    cin >> n >> m >> k;
    for (int i = 1; i <= k; i++) {
    	cin >> a[i] >> b[i];
    	a[i]--; b[i]--;
    	ma[a[i]][b[i]] = i;
    }
    for (int i = 0; i < n; i++) {
    	cin >> s[i];
    }
    bfs(a[1], b[1]);
    for (int i = 2; i <= k; i++) {
    	dis[a[i]][b[i]] = max(dis[a[i]][b[i]], k - i);
    }

    int ans = 0;

    for (int i = 0; i < n; i++) {
    	for (int j = 0; j < m; j++) {
    		int x = dis[i][j];
    		if (x != inf) {
    			ans += x * x;
    			//cout << i + 1 << " " << j + 1 << " " << x * x << endl;
    		}

    	}
    }

    cout << ans << endl;
}
signed main() {
    ios::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);
    int q = 1;
    //cin >> q;
    while (q --) {
        solve();
    }
    return 0;
}