#include<bits/stdc++.h>
#define endl '\n'
#define emdl '\n'
//#define int long long//
using namespace std;
typedef long long ll;
const int MAXN=15;
int h,w,d;
char mp[MAXN][MAXN];
int mhd(int xl,int xz,int yl,int yz){
	return abs(xl-xz)+abs(yl-yz);
}
signed main(){
	ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);//
	cin>>h>>w>>d;
	for(int i=1;i<=h;i++){
		for(int j=1;j<=w;j++){
			cin>>mp[i][j];
		}
	}
	int ans=-1,sum=0;
	for(int i=1;i<=h;i++){
		for(int j=1;j<=w;j++){
			if(mp[i][j]=='.'){
				for(int ii=i;ii<=h;ii++){
					for(int jj=j;jj<=w;jj++){
						if(ii==i&&jj==j) continue;
						if(mp[ii][jj]=='.'){
							sum=0;
							for(int iii=1;iii<=h;iii++){
								for(int jjj=1;jjj<=w;jjj++){
									if(mp[iii][jjj]='.'){
										if(mhd(i,iii,j,jjj)<=d||mhd(ii,iii,jj,jjj)<=d){
											sum++;
										}
									}
								}
							}
						}
						ans=max(sum,ans);
					}
				}
			}
		}
	}
	cout<<ans<<endl;
	return 0;
}

感觉思路没问题啊