#include <bits/stdc++.h>
#define rep(i,a,b) for (ll i = (a); i <= (b); ++i)
#define per(i,a,b) for (ll i = (b); i >= (a); --i)
#define all(x) begin(x),end(x)
#define pb push_back
using namespace std;
using ll = long long;
using vi = vector<ll>;
using ii = pair<ll,ll>;

set<ii> s, t;

signed main() {
    cin.tie(0)->sync_with_stdio(0);
    
    ll n, m, k;
    cin >> n >> m >> k;
    
    rep(i,1,n) rep(j,1,m) {
        char c; cin >> c;
        if (c == '#') {
            s.insert({i,j});
        }
    }
    
    rep(d,1,min(50ll,k)) {
        for (auto [x,y] : s) {
            rep(i,-1,+1) rep(j,-1,+1)
                t.insert({x+i,y+j});
        }
        swap(s,t);
    }
    
    ll ans = size(s);
    ll around = 0;
    ll add = 0;
    
    rep(i,-60,+80) {
        rep(j,-60,+80) {
            if (!s.count({i,j}))
            {
                ll flag = 0;
                rep(x,-1,+1) rep(y,-1,+1) {
                    if (s.count({i+x,j+y})) {
                        flag++;
                    }
                }
                if (flag) {
                    around++;
                    if (flag==2) add++;
                    assert(flag<=3);
                }
            }
        }
    }
    
    rep(d,min(50ll,k)+1,k) {
        ans += around;
        around += add;
    }
    
    cout << ans;
}