#include <cstdio>
#include <vector>
#include <queue>
#include <cstring>
#include <iostream>
#include <algorithm>

#define PB push_back
#define X first
#define Y second

using namespace std;

typedef pair < int, int > pii;
typedef unsigned long long ull;

const int N = 3050;
const int px[4] = {0, 0, 1, -1};
const int py[4] = {1, -1, 0, 0};

int n, m, k;
vector < pii > zm;
int S[N][N], dis[N][N], pos[N][N], treba[N][N], ans[N][N];
queue < pii > Q;

int main(){
	memset(dis, -1, sizeof(dis));
	memset(treba, -1, sizeof(treba));
	ios_base::sync_with_stdio(false); cin.tie(0);
	cin >> n >> m >> k;
	for(int i = k - 1;i >= 0;i--) {
		int x, y; cin >> x >> y;
		x--, y--; 
		if(i + 1 < k) {
			pos[x][y] = k - i;
			treba[x][y] = max(k - 2, 0) + (k - i - 1); 	
		}	
		zm.PB({x, y});
	}
	reverse(zm.begin(), zm.end());
	for(int i = 0;i < n;i++) {
		string tmp; cin >> tmp;
		for(int j = 0;j < m;j++)
			S[i][j] = (tmp[j] == '#');
	}
	int hx = zm.back().X, hy = zm.back().Y;
	dis[hx][hy] = 0; Q.push({hx, hy});
	for(;!Q.empty();Q.pop()) {
		int cx = Q.front().X, cy = Q.front().Y;
		//cout << cx << " " << cy << endl;
		for(int t = 0;t < 4;t++) {
			int nx = cx + px[t], ny = cy + py[t];
			if(nx < 0 || nx >= n || ny < 0 || ny >= m || S[nx][ny]) continue;
			if(pos[nx][ny]) {
				if(cx != hx || cy != hy || pos[nx][ny] != 2) {
					treba[nx][ny] = min(treba[nx][ny], max(k - pos[nx][ny] - dis[cx][cy], 0) + dis[cx][cy] + 1);
				//	cout << k << " " << pos[nx][ny] << " " << dis[cx][cy] << endl;
				//	cout << " T " << treba[nx][ny] << endl;
				//	cout << nx << " " << ny << endl;
				}
			} else if(dis[nx][ny] == -1){
				dis[nx][ny] = dis[cx][cy] + 1;
				Q.push({nx, ny});
			}
		}
	}
	for(int i = 1;i + 1 < k;i++) {
		treba[zm[i].X][zm[i].Y] = min(treba[zm[i].X][zm[i].Y], treba[zm[i - 1].X][zm[i - 1].Y] + 1);
	}
	for(int i = k - 3;i >= 0;i--) {
		treba[zm[i].X][zm[i].Y] = min(treba[zm[i].X][zm[i].Y], treba[zm[i + 1].X][zm[i + 1].Y] + 1);
	}
	for(int i = 0;i < n;i++) {
		for(int j = 0;j < m;j++) {
			if(pos[i][j]) {
				Q.push({i, j});
			} else {
				treba[i][j] = -1;
			}
		}
	}
	for(;!Q.empty();Q.pop()) {
		int cx = Q.front().X, cy = Q.front().Y;
		for(int k = 0;k < 4;k++) {
			int nx = cx + px[k], ny = cy + py[k];
			if(nx < 0 || nx >= n || ny < 0 || ny >= m || S[nx][ny] || treba[nx][ny] != -1) continue;
			treba[nx][ny] = treba[cx][cy] + 1;
			Q.push({nx, ny});
			
		}
	}
	ull ans = 0;
	for(int i = 0;i < n;i++) {
		for(int j = 0;j < m;j++) {
			if(dis[i][j] != -1 && treba[i][j] != -1) {
				ull x = min(dis[i][j], treba[i][j]);
			//	printf("%d ", min(dis[i][j], treba[i][j]));
				ans += x * x;
			} else if(dis[i][j] != -1) {
				ans += (ull)dis[i][j] * dis[i][j];
			//	printf("%d ", max(dis[i][j], treba[i][j]));
			} else if(treba[i][j] != -1){
				ans += (ull)treba[i][j] * treba[i][j];
			//	printf("%d ", max(dis[i][j], treba[i][j]));
			} else {
			//	printf("x ");
			}
		}
	//	printf("\n");
	}
	//printf("%llu\n", ans);
	cout << ans << endl;
	return 0;
}