#include <bits/stdc++.h>
using namespace std;
#define For(i,a,b) for (int i = (a); i <= (b); i++)
#define fi first
#define se second
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef pair<int, pii> pui;

const int N = 3010, M = 1e5 + 10;
int n, m, k, cx, cy;
int dx[] = {0, 1, 0, -1},
    dy[] = {1, 0, -1, 0};
struct Node {
    int x, y, idx;
} node[M];
string ss[N];
bool st[N][N], body[N][N];
int dis[N][N];

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin >> n >> m >> k;
    map<pii, int> M;
    For (i, 1, k) {
        int x, y; cin >> x >> y;
        M[{x, y}] = i;
        if (i == 1) {
            cx = x, cy = y;
        }
        node[i] = {x, y, i};
    }
    for (int i = 1; i <= n; i++) {
        cin >> ss[i];
        ss[i] = ' ' + ss[i];
    }
    memset(dis, 0x3f, sizeof(dis));
    priority_queue<pui, vector<pui>, greater<pui>> q;
    dis[cx][cy] = 0;
    q.push({0, {cx, cy}});
    while (q.size()) {
        auto t = q.top(); q.pop();
        int xx = t.se.fi, yy = t.se.se; int w = t.fi;
        if (st[xx][yy]) continue;
        st[xx][yy] = true;
        for (int i = 0; i < 4; i++) {
            int nx = xx + dx[i], ny = yy + dy[i];
            //cout << nx << " " << ny << endl;
            if (nx < 1 || ny < 1 || nx > n || ny > m || ss[nx][ny] == '#') continue;
            int nw = 0;
            if (M[{nx, ny}]) {
                int idx = M[{nx, ny}];
                nw = dis[xx][yy] + max(1, k - idx - w + 1);
                //cout << "nw = " << nw << endl;
            } else {
                nw = dis[xx][yy] + 1;
            }
            if (nw < dis[nx][ny]) {
                dis[nx][ny] = nw;
                q.push({nw, {nx, ny}});
            }
        }
    }
    ull ans = 0;
    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= m; j++) {
            if (dis[i][j] == 0x3f3f3f3f) continue;
            ans += (ull)dis[i][j] * dis[i][j];
        }
    cout << ans << "\n";
    return 0;
}