#include <bits/stdc++.h>
using namespace std;
const int maxn=3005;
const int a[4][2]={{0,1},{1,0},{0,-1},{-1,0}};
int read(){
    int ret=0,f=1;char ch=getchar();
    while(!isdigit(ch)){if(ch=='-')f=-f;ch=getchar();}
    while( isdigit(ch)){ret=(ret<<3)+(ret<<1)+(ch&15);ch=getchar();}
    return ret*f;
}
int n,m,k,hep_size;
struct node{
	int x,y; 
}que[maxn*maxn],p[100005];
int hep[100005],bel[maxn][maxn],dis[maxn][maxn];
bool vis[maxn][maxn];
void put(int id){
	hep[++hep_size]=id;int son=hep_size;
	while(son!=1&&hep[son]>hep[son>>1]) swap(hep[son],hep[son>>1]),son>>=1;
}
int get(){
	int ret=hep[1];hep[1]=hep[hep_size--];int fa=1,son;
	while((fa<<1)<=hep_size){
		if((fa<<1|1)>hep_size||hep[fa<<1]>hep[fa<<1|1]) son=fa<<1;else son=fa<<1|1;
		if(hep[son]>hep[fa]) swap(hep[son],hep[fa]),fa=son;else break;
	}
	return ret; 
}
bool check(int x,int y){
	return 1<=x&&x<=n&&1<=y&&y<=m&&!vis[x][y];
}
void BFS(){
	int hed=0,til=0;
	que[++til]=p[1];
	vis[p[1].x][p[1].y]=1;
	while(hed<til||hep_size){
		if(hed==til) que[++til]=p[get()];
		node now=que[++hed];
		if(hep_size&&dis[now.x][now.y]>=dis[p[hep[1]].x][p[hep[1]].y]){
			que[++til]=p[get()];
		}
		for(int p=0;p<4;++p){
			int x_=now.x+a[p][0],y_=now.y+a[p][1];
			if(!check(x_,y_)) continue;
			if(bel[x_][y_]){
				put(bel[x_][y_]);
				dis[x_][y_]=max(dis[now.x][now.y]+1,k-bel[x_][y_]+1);
			}else{
				que[++til]=(node){x_,y_};
				dis[x_][y_]=dis[now.x][now.y]+1;
			}
			vis[x_][y_]=1;
		}
	}
}
unsigned long long ans;
int main(){
	n=read(),m=read(),k=read();
	for(int i=1;i<=k;++i){
		p[i].x=read();
		p[i].y=read(); 
		bel[p[i].x][p[i].y]=i;
	}
	for(int i=1;i<=n;++i){
		for(int j=1;j<=m;++j){
			char ch=getchar();
			while(ch!='#'&&ch!='.') ch=getchar();
			if(ch=='#')	vis[i][j]=1;	
		}
	}	
	BFS();
	for(int i=1;i<=n;++i){
		for(int j=1;j<=m;++j){
			ans+=1ll*dis[i][j]*dis[i][j];
		}
	}
	printf("%llu\n",ans);
	return 0;
}