// Slower C++ solution:
#define _CRT_SECURE_NO_WARNINGS

#include <iostream>

#include <sstream>

#include <iomanip>

#include <cstdio>

#include <cstdlib>

#include <cmath>

#include <cctype>

#include <cstring>

#include <vector>

#include <list>

#include <queue>

#include <deque>

#include <stack>

#include <map>

#include <set>

#include <algorithm>

#include <iterator>

#include <bitset>

#include <ctime>

#include<complex>

using namespace std;



#define FOR(i,a,b) for (int i = (a); i < (b); i++)

#define RFOR(i,b,a) for (int i = (b)-1; i >= (a); i--)

#define ITER(it,a) for (__typeof(a.begin()) it = a.begin(); it != a.end(); it++)

#define FILL(a,value) memset(a, value, sizeof(a))



#define SZ(a) (int)a.size()

#define ALL(a) a.begin(), a.end()

#define PB push_back

#define MP make_pair



typedef long long LL;

typedef vector<int> VI;

typedef pair<int, int> PII;



const double PI = acos(-1.0);

const int INF = 1000 * 1000 * 1000 + 7;

const LL LINF = INF * (LL)INF;



const int MAX = 1000 + 47;

const int MOD = 1000 * 1000 * 1000 + 7;



string A[MAX];

struct Matrix

{

	LL T[2][2];

	Matrix()

	{

		FOR(i, 0, 2) FOR(j, 0, 2) T[i][j] = 0;

	}



	void one()

	{

		T[0][0] = T[1][1] = 1;

	}



	void operator *=(Matrix a)

	{

		LL R[2][2] = {0};

		FOR(i, 0, 2)

		{

			FOR(j, 0, 2)

			{

				FOR(k, 0, 2)

				{

					R[i][j] = (R[i][j] + T[i][k] * a.T[k][j]) % MOD;

				}

			}

		}



		FOR(i, 0, 2)

		{

			FOR(j, 0, 2) T[i][j] = R[i][j];

		}

	}



	void print()

	{

		FOR(i, 0, 2)

		{

			FOR(j, 0, 2) cout << T[i][j] << " ";

			cout << endl;

		}

	}

};



void bp(Matrix& A, LL k)

{

	Matrix R;

	R.one();



	while (k)

	{

		if (k & 1)

		{

			R *= A;

		}



		k >>= 1;

		A *= A;

	}



	FOR(i, 0, 2)

	{

		FOR(j, 0, 2) A.T[i][j] = R.T[i][j];

	}

}



int main()

{

	//freopen("in.txt", "r", stdin);

	//freopen("out.txt", "w", stdout);

	ios::sync_with_stdio(false); cin.tie(0);

	int n, m;

	LL k;

	cin >> n >> m >> k;



	FOR(i, 0, n) cin >> A[i];

	LL cnt = 0;

	bool ver = false;

	bool hor = false;

	FOR(i, 0, n)

	{

		if (A[i][0] == A[i][m - 1] && A[i][0] == '#') hor = true;

	}



	FOR(j, 0, m)

	{

		if (A[0][j] == A[n - 1][j] && A[0][j] == '#') ver = true;

	}

	

	FOR(i, 0, n)

	{

		FOR(j, 0, m) cnt += A[i][j] == '#';

	}



	if (ver && hor)

	{

		cout << 1 << endl;

		return 0;

	}



	if (!ver && !hor)

	{

		Matrix res;

		res.T[0][0] = cnt;

		bp(res, k - 1);

		cout << res.T[0][0] << endl;

		return 0;

	}



	LL w = 0;

	LL b = 0;



	if (hor)

	{

		FOR(i,0,n)

		{

			FOR(j, 1, m)

			{

				if (A[i][j] == A[i][j - 1] && A[i][j] == '#') w++;

			}



			if (A[i][0] == A[i][m - 1] && A[i][0] == '#') b++;

		}

	}

	else

	{

		FOR(j, 0, m)

		{

			FOR(i, 1, n)

			{

				if (A[i - 1][j] == A[i][j] && A[i][j] == '#') w++;

			}



			if (A[0][j] == A[n - 1][j] && A[0][j] == '#') b++;

		}

	}



	Matrix res;

	res.T[0][0] = b;

	res.T[0][1] = w;

	res.T[1][0] = 0;

	res.T[1][1] = cnt;

	//res.print();



	bp(res, k - 1);

	w = res.T[0][1];

	b = res.T[1][1];

	cout << (b - w + MOD) % MOD << endl;

}

// Faster C++ solution for the same problem (measured speedup: 5.41665059879718x):
#include<cstdio>

#include<cstring>

#include<algorithm>

using namespace std;



typedef long long ll;

const int MAXN=1005;

const int MOD=1e9+7;



int h,w;

ll k;

char s[MAXN][MAXN];



ll ksm(ll x,ll y){

    ll res=1;

    while(y){

        if(y&1) res=res*x%MOD;

        x=x*x%MOD;

        y>>=1ll;

    }

    return res;

}



struct Mat{

    ll a[2][2];

    Mat friend operator * (Mat x,Mat y){

        Mat c; memset(c.a,0,sizeof c.a);

        for(int i=0;i<2;i++)

            for(int j=0;j<2;j++)

                for(int k=0;k<2;k++)

                    c.a[i][j]=(c.a[i][j]+x.a[i][k]*y.a[k][j])%MOD;

        return c;

    }

};



int wk1(){

	int C=0;

	for(int i=0;i<h;i++)

		for(int j=0;j<w;j++)

			C+=s[i][j];

	return ksm(C,(k-1)%(MOD-1));

}



int wk(int lr,int ud){

	int C=0;

	for(int i=0;i<h;i++)

		for(int j=0;j<w;j++)

			C+=s[i][j];

	int V=ksm(C,(k-1)%(MOD-1));

	int E0=0;

	if(lr){

		for(int i=0;i<h;i++)

			for(int j=0;j<w-1;j++)

				E0+=(s[i][j]&s[i][j+1]);

	}else{

		for(int i=0;i<h-1;i++)

			for(int j=0;j<w;j++)

				E0+=(s[i][j]&s[i+1][j]);

	}

	Mat S,T;

	memset(S.a,0,sizeof S.a);

	memset(T.a,0,sizeof T.a);

	S.a[0][0]=E0,S.a[0][1]=C;

	T.a[0][0]=lr+ud,T.a[1][0]=E0,T.a[1][1]=C;

	ll t=k-2;

	while(t){

		if(t&1)S=S*T;

		T=T*T;t>>=1;

	}

	return (V-S.a[0][0]+MOD)%MOD;

}



int main(){

	scanf("%d%d%lld",&h,&w,&k);

	for(int i=0;i<h;i++) scanf("%s",s[i]);

	if(k==1) return puts("1"),0;

	for(int i=0;i<h;i++)

        for(int j=0;j<w;j++)

            s[i][j]=(int)(s[i][j]=='#');

	int lr=0,ud=0;

	for(int i=0;i<w;i++) ud+=(s[0][i]&s[h-1][i]);

	for(int i=0;i<h;i++) lr+=(s[i][0]&s[i][w-1]);

	if(lr&&ud) puts("1");

	else if(!lr&&!ud) printf("%d\n",wk1());

	else printf("%d\n",wk(lr,ud));

}