#include<bits/stdc++.h>
#define ll long long
#define fio std::ios::sync_with_stdio(false);cin.tie(0);cout.tie(0)
#define pii pair<int,int>
using namespace std;
template<typename T>void read(T &x){
    x=0;
    char c=getchar();
    T ret=0;
    while(!isdigit(c))ret|=!(c^'-'),c=getchar();
    while(isdigit(c))x=(x<<3)+(x<<1)+(c^48),c=getchar();
    if(ret)x=(~x)+1;
}
template<typename T,typename ...Args>
void read(T &x,Args &...xs){
    read(x);read(xs...);
}
template<typename T>void print(T x){
    if(x<0)putchar('-'),x=(~x)+1;
    if(x>9)print(x/10);
    putchar((x-x/10*10)^48);
}
template<typename T>void wr1(T x){
    print(x);putchar(' ');
}
template<typename T>void wr2(T x){
    print(x);putchar('\n');
}
const int N=3005;
int n,m,k,c1[]={1,0,-1,0},c2[]={0,1,0,-1},snac[N][N],sx,sy;
unsigned ll dis[N][N];
char mp[N][N];
bool chek(int x,int y) {
    if(x<1||y<1||x>n||y>m||mp[x][y]=='#')return 0;
    return 1;
}
queue<pii>q1,q2;
int main(){
    read(n,m,k);
    for(int i=1;i<=n;++i) {
        for(int j=1;j<=m;++j) {
            dis[i][j]=LONG_LONG_MAX;
            snac[i][j]=k;
        }
    }
    for(int i=1;i<=k;++i){
        int x,y;
        read(x,y);
        if(!sx)sx=x;
        if(!sy)sy=y;
        snac[x][y]=i;
    }
    for(int i=1;i<=n;++i) {
        scanf("%s",mp[i]+1);
    }
    dis[sx][sy]=0;
    q1.push({sx,sy});
    while(!q1.empty()){
        int x=q1.front().first,y=q1.front().second;
        int X=0,Y=0;
        if(!q2.empty()) {
            X=q2.front().first,Y=q2.front().second;
            if(dis[x][y]<dis[X][Y])q1.pop();
            else q2.pop(),x=X,y=Y;
        }
        if(!(X|Y))q1.pop();
        for(int i=0;i<=3;++i) {
            X=x+c1[i],Y=y+c2[i];
            if(chek(X,Y)) {
                if(dis[X][Y]>dis[x][y]+1) {
                    if(dis[x][y]>=k-snac[X][Y]) {
                        dis[X][Y]=dis[x][y]+1;
                        q1.push({X,Y});
                    }
                    else {
                        dis[X][Y]=k-snac[X][Y]+1;
                        q2.push({X,Y});
                    }
                }
            }
        }
    }
    unsigned ll ans=0;
    for(int i=1;i<=n;++i) {
        for(int j=1;j<=m;++j) {
            if(dis[i][j]>=LONG_LONG_MAX)continue;
            ans+=dis[i][j]*dis[i][j];
        }
    }
    print(ans);
    return 0;
}