//#pragma GCC optimize("Ofast", "unroll-loops")
//#pragma GCC target("sse", "sse2", "sse3", "ssse3", "sse4")

#ifdef __APPLE__

#include <iostream>
#include <cmath>
#include <algorithm>
#include <stdio.h>
#include <cstdint>
#include <cstring>
#include <string>
#include <cstdlib>
#include <vector>
#include <bitset>
#include <map>
#include <queue>
#include <ctime>
#include <stack>
#include <set>
#include <list>
#include <random>
#include <deque>
#include <functional>
#include <iomanip>
#include <sstream>
#include <fstream>
#include <complex>
#include <numeric>
#include <cassert>
#include <array>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <thread>

#else
#include <bits/stdc++.h>
#endif

#define all(a) a.begin(),a.end()
#define len(a) (int)(a.size())
#define mp make_pair
#define pb push_back
#define fir first
#define sec second
#define fi first
#define se second

using namespace std;

typedef pair<int, int> pii;
typedef long long ll;
typedef long double ld;

template<typename T>
bool umin(T &a, T b) {
    if (b < a) {
        a = b;
        return true;
    }
    return false;
}

template<typename T>
bool umax(T &a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}

#if __APPLE__
#define D for (bool _FLAG = true; _FLAG; _FLAG = false)
#define LOG(...) print(#__VA_ARGS__" ::", __VA_ARGS__) << endl

template<class ...Ts>
auto &print(Ts ...ts) { return ((cerr << ts << " "), ...); }

#else
#define D while (false)
#define LOG(...)
#endif

const int max_n = -1, inf = 1000111222;

//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

void solve() {
    int r, c, k;
    cin >> r >> c >> k;
    int R = r, C = c + (k + 2) * 2;
    vector<vector<int> > time(r, vector<int>(C, -1));
    queue<pair<int, int> > q;
    for(int i = 0; i < r; i++)
        for(int j = 0; j < c; j++) {
            char x; cin >> x;
            if(x == '#') {
                time[i][j + k] = 0;
                q.emplace(i, j + k);
            }
        }
    int dx[8] = {-1, -1, -1, 0, 1, 1, 1, 0}, dy[8] = {-1, 0, 1, 1, 1, 0, -1, -1};
    ll ans = 0;
    while(!q.empty()) {
        auto cr = q.front(); q.pop();
        int cx = cr.fi, cy = cr.se;
        if(time[cx][cy] == k) break;
        for(int mv = 0; mv < 8; mv++) {
            int nx = cx + dx[mv], ny = cy + dy[mv];
            if(nx >= 0 && nx < R && ny >= 0 && ny < C && time[nx][ny] == -1) time[nx][ny] = time[cx][cy] + 1, q.emplace(nx, ny);
        }
    }
    for(int i = 0; i < R; i++) {
        for(int j = 0; j < C; j++) {
            ans += (time[i][j] != -1);
        }
    }
    multiset<int> av;
    vector<vector<int> > to_add(C), to_del(C);
    for(int j = 0; j < C; j++) {
        if(time[0][j] == -1 || time[0][j] == k) continue;
        int step = k - time[0][j];
        to_add[j - step].pb(step);
        to_del[j + step].pb(step);
    }
    for(int j = 0; j < C; j++) {
        for(auto& x : to_add[j]) av.insert(x);
        ans += (!av.empty() ? (*av.rbegin()) : 0);
        for(auto& x : to_del[j]) av.erase(av.find(x));
        to_add[j].clear(); to_del[j].clear();
    }
    av.clear();
    for(int j = 0; j < C; j++) {
        if(time[r - 1][j] == -1 || time[r - 1][j] == k) continue;
        int step = k - time[r - 1][j];
        to_add[j - step].pb(step);
        to_del[j + step].pb(step);
    }
    for(int j = 0; j < C; j++) {
        for(auto& x : to_add[j]) av.insert(x);
        ans += (!av.empty() ? (*av.rbegin()) : 0);
        for(auto& x : to_del[j]) av.erase(av.find(x));
        to_add[j].clear(); to_del[j].clear();
    }
    cout << ans << '\n';
}

signed main() {
//   freopen("input.txt", "r", stdin);
//   freopen("output.txt", "w", stdout);

    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    int t = 1;

    //cin >> t;

    while (t--) solve();

}

/*
KIVI
*/