#include<cstdio>
#include<vector>
#include<queue>
#include<cstring>
#include<iostream>
#include<algorithm>
#include<ctime>
#include<random>
#include<array>
#include<assert.h>
#define pb emplace_back
#define mp make_pair
#define fi first
#define se second
#define dbg(x) cerr<<"In Line "<< __LINE__<<" the "<<#x<<" = "<<x<<'\n'
#define dpi(x,y) cerr<<"In Line "<<__LINE__<<" the "<<#x<<" = "<<x<<" ; "<<"the "<<#y<<" = "<<y<<'\n'
#define DE(fmt,...) fprintf(stderr, "Line %d : " fmt "\n",__LINE__,##__VA_ARGS__)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int>pii;
typedef pair<ll,int>pli;
typedef pair<ll,ll>pll;
typedef pair<int,ll>pil;
typedef vector<int>vi;
typedef vector<ll>vll;
typedef vector<pii>vpii;
typedef vector<pll>vpll;
template<typename T>T cmax(T &x, T y){return x=x>y?x:y;}
template<typename T>T cmin(T &x, T y){return x=x<y?x:y;}
template<typename T>
T &read(T &r){
	r=0;bool w=0;char ch=getchar();
	while(ch<'0'||ch>'9')w=ch=='-'?1:0,ch=getchar();
	while(ch>='0'&&ch<='9')r=r*10+(ch^48),ch=getchar();
	return r=w?-r:r;
}
template<typename T1,typename... T2>
void read(T1 &x,T2& ...y){read(x);read(y...);}
const int N=3010;
const int inf=0x3f3f3f3f;
int n,m,q;
char s[N][N];
pii a[100010];
int dis[N][N],co[N][N],pt[N][N],vis[N][N];
int dx[]={1,-1,0,0};
int dy[]={0,0,1,-1};
signed main(){
	#ifdef do_while_true
//		assert(freopen("data.in","r",stdin));
//		assert(freopen("data.out","w",stdout));
	#endif
	read(n,m,q);
	for(int i=1;i<=q;i++)read(a[i].fi,a[i].se),pt[a[i].fi][a[i].se]=i;
	for(int i=1;i<=n;i++)scanf("%s",s[i]+1);
	for(int i=1;i<=n;i++)for(int j=1;j<=m;j++)dis[i][j]=inf;
	int sx=a[1].fi,sy=a[1].se;
	dis[sx][sy]=0;
	struct ele{
		int x,y,d;
		bool operator<(const ele &z)const{
			return d>z.d;
		}
	};
	queue<ele>Q;
	Q.push({sx,sy,0});
	while(!Q.empty()){
		auto qt=Q.front();Q.pop();
		int x=qt.x,y=qt.y,w=q-co[x][y];
		if(vis[x][y])continue;
		vis[x][y]=1;
		for(int i=0;i<4;i++){
			int u=x+dx[i],v=y+dy[i];
			if(u<1||v<1||u>n||v>m||s[u][v]=='#')continue;
			int td=dis[x][y]+1;
			int tc=co[x][y];
			int nw=w;
			if(pt[u][v]&&pt[u][v]+td<=w){
				tc+=w-(pt[u][v]+td)+1;
				nw-=w-(pt[u][v]+td)+1;
			}
			if(td+tc<dis[u][v]+co[u][v]
				||(td+tc==dis[u][v]+co[u][v]&&tc>dis[u][v])){
				dis[u][v]=td;
				co[u][v]=tc;
				Q.push({u,v,td+tc});
			}
		}
	}
	ull sum=0;
	for(int i=1;i<=n;i++)
		for(int j=1;j<=m;j++)if(dis[i][j]!=inf){
			ull x=dis[i][j]+co[i][j];
//			cerr<<x<<' ';
			sum+=x*x;
		}
	cout<<sum<<'\n';
    #ifdef do_while_true
//		cerr<<'\n'<<"Time:"<<1.0*clock()/CLOCKS_PER_SEC*1000<<" ms"<<'\n';
	#endif
	return 0;
}