#include <bits/stdc++.h>
#define ADD(a, b) a = (a + ll(b)) % mod
#define MUL(a, b) a = (a * ll(b)) % mod
#define MAX(a, b) a = max(a, b)
#define MIN(a, b) a = min(a, b)
#define rep(i, a, b) for(int i = int(a); i < int(b); i++)
#define rer(i, a, b) for(int i = int(a) - 1; i >= int(b); i--)
#define all(a) (a).begin(), (a).end()
#define sz(v) (int)(v).size()
#define pb push_back
#define sec second
#define fst first
#define debug(fmt, ...) Debug(__LINE__, ":", fmt, ##__VA_ARGS__)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef pair<int, pi> ppi;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<vl> mat;
typedef complex<double> comp;
void Debug() {cout << '\n'; }
template<class FIRST, class... REST>void Debug(FIRST arg, REST... rest){
	cout<<arg<<" ";Debug(rest...);}
template<class T>ostream& operator<<(ostream& out,const vector<T>& v) {
	out<<"[";if(!v.empty()){rep(i,0,sz(v)-1)out<<v[i]<<", ";out<<v.back();}out<<"]";return out;}
template<class S, class T>ostream& operator<<(ostream& out,const pair<S, T>& v){
	out<<"("<<v.first<<", "<<v.second<<")";return out;}
const int MAX_N = 200010;
const int MAX_V = 100010;
const double eps = 1e-6;
const ll mod = 1000000007;
const int inf = 1 << 29;
const ll linf = 1LL << 60;
const double PI = 3.14159265358979323846;
///////////////////////////////////////////////////////////////////////////////////////////////////

int H, W;
ll K;
int B[1010][1010];

ll mod_pow(ll a, ll n) {
	if(n == 0) return 1;
	ll res = mod_pow(a, n / 2);
	if(n % 2 == 0) return res * res % mod;
	else return a * res % mod * res % mod;
}

mat mat_mul(const mat &A, const mat &B) {//if invalid, assert. taking mod.
	assert((int)A[0].size() == (int)B.size());
	mat C(A.size(), vl(B[0].size()));
	rep(i, 0, (int)A.size()) {
		rep(k, 0, (int)B.size()) {
			rep(j, 0, (int)B[0].size()) {
				C[i][j] = (C[i][j] + A[i][k] * B[k][j]) % mod;
			}
		}
	}
	return C;
}

mat mat_pow(mat A, ll n) {
	mat B((int)A.size(), vl((int)A.size()));
	rep(i, 0, (int)A.size()) {
		B[i][i] = 1;
	}
	while(n > 0) {
		if(n & 1) B = mat_mul(B, A);
		A = mat_mul(A, A);
		n >>= 1;
	}
	return B;
}

void solve() {
	cin >> H >> W >> K;
	ll p = 0;
	rep(i, 0, H) {
		string str;
		cin >> str;
		rep(j, 0, W) {
			if(str[j] == '#') B[i][j] = 1;
			p += B[i][j];
		}
	}
	int bh = 0, bw = 0;
	rep(j, 0, W) {
		if(B[0][j] == 1 && B[H - 1][j] == 1) bh++;
	}
	rep(i, 0, H) {
		if(B[i][0] == 1 && B[i][W - 1] == 1) bw++;
	}
	if(H == 1) {
		if(bw) cout << 1 << "\n";
		else cout << mod_pow(p, K - 1) << "\n";
	}
	else if(W == 1) {
		if(bh) cout << 1 << "\n";
		else cout << mod_pow(p, K - 1) << "\n";
	}
	else {
		if(bw && bh) {
			cout << 1 << "\n";
		}
		else if(!bw && !bh) {
			cout << mod_pow(p, K - 1) << "\n";
		}
		else {
			int e = 0;
			int f;
			if(bh) {
				rep(i, 0, H - 1) {
					rep(j, 0, W) {
						if(B[i][j] == 1 && B[i + 1][j] == 1) e++;
					}
				}
				f = bh;
			}
			else {
				rep(j, 0, W - 1) {
					rep(i, 0, H) {
						if(B[i][j] == 1 && B[i][j + 1] == 1) e++;
					}
				}
				f = bw;
			}
			// debug(bh, bw, p, e);
			mat A(2, vl(2, 0));
			A[0][0] = p;
			A[0][1] = mod - 1;
			A[1][0] = 0;
			A[1][1] = f;
			mat B = mat_pow(A, K - 1);
			cout << (B[0][0] + B[0][1] * e % mod) % mod << "\n";
		}
	}
}

int main() {
#ifndef LOCAL
	ios::sync_with_stdio(false);
    cin.tie(0);
#endif
    cout << fixed;
	cout.precision(20);
	srand((unsigned int)time(NULL));
#ifdef LOCAL
	//freopen("in.txt", "wt", stdout); //for tester
    freopen("in.txt", "rt", stdin);
#endif	
	solve();
#ifdef LOCAL
    cerr << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n";
#endif
	return 0;
}



Measured memory_bytes: 4224