#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef double db;
const int N = 5e5 + 5;
const int mod = 1e9+7;
const double eps =0.00001;
#define int long long
#define ull unsigned long long
#define endl '\n'
using i64 = int64_t;
int ksm(int a,int b){
    int ans=1;
    while(b){
        if(b%2)ans=ans*a%mod;
        a=a*a%mod;
        b/=2;
    }
    return ans;
}
struct node{
    int cnt=0,x,y,k;
    inline bool operator<(const node &x)const {
        return cnt>x.cnt;
    }
};
vector<vector<char>>pic;
vector<vector<int>>idx,dis,vis;
int dx[4]={0,0,1,-1};
int dy[4]={1,-1,0,0};
void solve() {
    int n,m,k;
    cin>>n>>m>>k;
    pic=vector<vector<char>>(n+5,vector<char>(m+5));
    vis=dis=idx=vector<vector<int>>(n+5,vector<int>(m+5));
    int x,y;
    for(int i=1,x1,y1;i<=k;i++){
        if(i==1){
            cin>>x>>y;
            idx[x][y]=i;
        }else{
            cin>>x1>>y1;
            idx[x1][y1]=i;
        }
    }
    priority_queue<node>q;
    for(int i=1;i<=n;i++){
        for(int j=1;j<=m;j++){
            cin>>pic[i][j];
            dis[i][j]=1e9;
                if(idx[i][j]>1){
                    dis[i][j]=max(k-2+idx[i][j]-1,1ll*0);
                    //q.push({ dis[i][j],i,j,2});
                }
        }
    }
    dis[x][y]=0;
    q.push({0,x,y,k});
    while(!q.empty()){
        auto y=q.top();
        q.pop();
        if(vis[y.x][y.y])continue;
        vis[y.x][y.y]=1;
        for(int i=0;i<4;i++){
            int x1=y.x+dx[i],y1=y.y+dy[i];
            if(x1<1||x1>n||y1<1||y1>m||pic[x1][y1]=='#')continue;
            if(idx[x1][y1]){
                if(y.k-idx[x1][y1]-y.cnt<=0){
                    if(dis[x1][y1]>dis[y.x][y.y]+1){
                        dis[x1][y1]=dis[y.x][y.y]+1;
                        q.push({dis[x1][y1],x1,y1,y.k});
                    }
                }else{
                    int p=y.k-idx[x1][y1]-y.cnt;
                    if(dis[x1][y1]>dis[y.x][y.y]+1+p){
                        dis[x1][y1]=dis[y.x][y.y]+1+p;
                        q.push({dis[x1][y1],x1,y1,y.k-p});
                    }
                }
            }else{
                if(dis[x1][y1]>dis[y.x][y.y]+1){
                    dis[x1][y1]=dis[y.x][y.y]+1;
                    q.push({dis[x1][y1],x1,y1,y.k});
                }
            }
        }
    }
    ull  ans=0;
    for(int i=1;i<=n;i++){
        for(int j=1;j<=m;j++){
            if(dis[i][j]==1e9)continue;
            ans+=(ull)(dis[i][j]*dis[i][j]);
        }
    }
    cout<<ans<<endl;
}
signed main() {
    std::ios::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);
    cout<<fixed<<setprecision(11);
    int T = 1;
    //  cin >> T;
    while (T--) solve();
    return 0;
}