#include <bits/stdc++.h>

using namespace std;
using ll = unsigned long long;

int main()
{
    ll r, z, k;
    cin >> r >> z >> k; // r*z size of vector | k*k size of racket
    ll rg = k - 2;      // range of search (r*r)
    ll s;               // s=max amount per range  idx= index of upper right corner of the final    "s" range
    pair<ll, ll> idx;   // idx= index of upper left corner of the ultimate   "s" range
    vector<vector<string>> z1(r);
    for (int i = 0; i < r; i++)
    {
        for (int j = 0; j < z; j++)
        {
            string a;
            cin >> a;

            z1.at(i).push_back(a);
        }
    }

    // ll count = std::count(hlp.at(4), hlp.at(5), '*');
    ll fs = 0; // final sum
    for (int i = 1; i < r - 1; i++)
    {
        ll p1, p2; // caracter counting parameters

        for (int j = 1; j < z - rg - 1; j++)
        {
            p1 = j + 1;

            p2 = z - j;
            ll rc = 0;    // number of searchd rows
            ll count = 0; // total characters found
            for (int w = i; rc <= rg; w++ && rc++)
            {
                count += std::count(z1.at(i).begin() + p1, z1.at(i).begin() + p2, '*');
            }
            if (s < count)
            {
                s = count;
            }
        }
    }
    cout << s << endl;

    return 0;
}