#include <bits/stdc++.h>
using namespace std;

#define rep(i, a, b) for (int i = a; i < (b); ++i)
#define all(x) begin(x), end(x) 
#define sz(x); (int) (x).size()

typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef vector<int> vi;
string grid[3000];
int dx[4] = {0,0,1,-1};
int dy[4] = {1,-1,0,0};
pii d[3000][3000];
int id[3000][3000];
int n,m,k;
bool check(int i,int j){
	return i>=0 && j>=0 && i<n && j<m && grid[i][j] != '#';
}
int main()
{
	cin>>n>>m>>k;
	vector<int>X(k),Y(k);
	for(int i=0;i<k;i++){
		cin>>X[i]>>Y[i];
		X[i]--;
		Y[i]--;
	}
	for(int i=0;i<n;i++)cin>>grid[i];
	for(int i=0;i<n;i++){
		for(int j=0;j<m;j++){
			d[i][j] = {1e9,1e9};
		    id[i][j] = 1e9;
		}
	}
	for(int i=0;i<k;i++)id[X[i]][Y[i]] = i+1;
	d[X[0]][Y[0]] = {0,k};
	
	priority_queue<array<int,4>>pq;
	pq.push({0,-k,X[0],Y[0]});
	while(!pq.empty()){
		int x = pq.top()[2];
		int y = pq.top()[3];
		int d0 = -pq.top()[0];
		int len = -pq.top()[1];
		pq.pop();
		if(d[x][y] != make_pair(d0,len))continue;
		for(int j=0;j<4;j++){
			int xn = x+dx[j];
			int yn = y+dy[j];
			if(!check(xn,yn))continue;
			int need =(len-d0) - id[xn][yn];
			need = max(need,0);
			
			if(d[xn][yn] > make_pair(d0+need+1,len-need)){
				d[xn][yn] = {d0+need+1,len-need};
				pq.push({-d0-need-1,-(len-need),xn,yn});
			}
		}
	}
	unsigned long long int ans = 0;
	for(int i=0;i<n;i++){
		for(int j=0;j<m;j++){
			//cout<<d[i][j].first<<" ";
			if(d[i][j].first == 1e9)continue;
			ans += d[i][j].first * 1LL* d[i][j].first;
		}
		//cout<<'\n';
	}
	cout<<ans<<'\n';

	
	
	
}