#include <bits/stdc++.h>
using namespace std;

using ll=long long;
#define int ll

#define rng(i,a,b) for(int i=int(a);i<int(b);i++)
#define rep(i,b) rng(i,0,b)
#define gnr(i,a,b) for(int i=int(b)-1;i>=int(a);i--)
#define per(i,b) gnr(i,0,b)
#define pb push_back
#define eb emplace_back
#define a first
#define b second
#define bg begin()
#define ed end()
#define all(x) x.bg,x.ed
#ifdef LOCAL
#define dmp(x) cerr<<__LINE__<<" "<<#x<<" "<<x<<endl
#else
#define dmp(x) void(0)
#endif

template<class t,class u> void chmax(t&a,u b){if(a<b)a=b;}
template<class t,class u> void chmin(t&a,u b){if(b<a)a=b;}

template<class t> using vc=vector<t>;
template<class t> using vvc=vc<vc<t>>;

using pi=pair<int,int>;
using vi=vc<int>;

template<class t,class u>
ostream& operator<<(ostream& os,const pair<t,u>& p){
	return os<<"{"<<p.a<<","<<p.b<<"}";
}

template<class t> ostream& operator<<(ostream& os,const vc<t>& v){
	os<<"{";
	for(auto e:v)os<<e<<",";
	return os<<"}";
}

#define mp make_pair
#define mt make_tuple
#define one(x) memset(x,-1,sizeof(x))
#define zero(x) memset(x,0,sizeof(x))
#ifdef LOCAL
void dmpr(ostream&os){os<<endl;}
template<class T,class... Args>
void dmpr(ostream&os,const T&t,const Args&... args){
	os<<t<<" ";
	dmpr(os,args...);
}
#define dmp2(...) dmpr(cerr,"Line:",__LINE__,##__VA_ARGS__)
#else
#define dmp2(...) void(0)
#endif

using uint=unsigned;
using ull=unsigned long long;

template<int i,class T>
void print_tuple(ostream&,const T&){
}

template<int i,class T,class H,class ...Args>
void print_tuple(ostream&os,const T&t){
	if(i)os<<",";
	os<<get<i>(t);
	print_tuple<i+1,T,Args...>(os,t);
}

template<class ...Args>
ostream& operator<<(ostream&os,const tuple<Args...>&t){
	os<<"{";
	print_tuple<0,tuple<Args...>,Args...>(os,t);
	return os<<"}";
}

void print(ll x,int suc=1){
	cout<<x;
	if(suc==1)
		cout<<"\n";
	if(suc==2)
		cout<<" ";
}

ll read(){
	ll i;
	cin>>i;
	return i;
}

vi readvi(int n,int off=0){
	vi v(n);
	rep(i,n)v[i]=read()+off;
	return v;
}

template<class T>
void print(const vector<T>&v,int suc=1){
	rep(i,v.size())
		print(v[i],i==int(v.size())-1?suc:2);
}

string readString(){
	string s;
	cin>>s;
	return s;
}

template<class T>
T sq(const T& t){
	return t*t;
}

//#define CAPITAL
void yes(bool ex=true){
	#ifdef CAPITAL
	cout<<"YES"<<endl;
	#else
	cout<<"Yes"<<endl;
	#endif
	if(ex)exit(0);
}
void no(bool ex=true){
	#ifdef CAPITAL
	cout<<"NO"<<endl;
	#else
	cout<<"No"<<endl;
	#endif
	if(ex)exit(0);
}

constexpr ll ten(int n){
	return n==0?1:ten(n-1)*10;
}

const ll infLL=LLONG_MAX/3;

#ifdef int
const int inf=infLL;
#else
const int inf=INT_MAX/2-100;
#endif

int topbit(signed t){
	return t==0?-1:31-__builtin_clz(t);
}
int topbit(ll t){
	return t==0?-1:63-__builtin_clzll(t);
}
int botbit(signed a){
	return a==0?32:__builtin_ctz(a);
}
int botbit(ll a){
	return a==0?64:__builtin_ctzll(a);
}
int popcount(signed t){
	return __builtin_popcount(t);
}
int popcount(ll t){
	return __builtin_popcountll(t);
}
bool ispow2(int i){
	return i&&(i&-i)==i;
}
int mask(int i){
	return (int(1)<<i)-1;
}

bool inc(int a,int b,int c){
	return a<=b&&b<=c;
}

template<class t> void mkuni(vc<t>&v){
	sort(all(v));
	v.erase(unique(all(v)),v.ed);
}

ll rand_int(ll l, ll r) { //[l, r]
	#ifdef LOCAL
	static mt19937_64 gen;
	#else
    static random_device rd;
    static mt19937_64 gen(rd());
    #endif
    return uniform_int_distribution<ll>(l, r)(gen);
}

template<class t>
int lwb(const vc<t>&v,const t&a){
	return lower_bound(all(v),a)-v.bg;
}

using uint=unsigned;
using ull=unsigned long long;

//initfact();
//const uint mod=998244353;
const uint mod=1000000007;
//uint mod=1;
struct mint{
	uint v;
	mint(ll vv=0){s(vv%mod+mod);}
	mint& s(uint vv){
		v=vv<mod?vv:vv-mod;
		return *this;
	}
	mint operator-()const{return mint()-*this;}
	mint& operator+=(const mint&rhs){return s(v+rhs.v);}
	mint&operator-=(const mint&rhs){return s(v+mod-rhs.v);}
	mint&operator*=(const mint&rhs){
		v=ull(v)*rhs.v%mod;
		return *this;
	}
	mint&operator/=(const mint&rhs){return *this*=rhs.inv();}
	mint operator+(const mint&rhs)const{return mint(*this)+=rhs;}
	mint operator-(const mint&rhs)const{return mint(*this)-=rhs;}
	mint operator*(const mint&rhs)const{return mint(*this)*=rhs;}
	mint operator/(const mint&rhs)const{return mint(*this)/=rhs;}
	mint pow(int n)const{
		mint res(1),x(*this);
		while(n){
			if(n&1)res*=x;
			x*=x;
			n>>=1;
		}
		return res;
	}
	mint inv()const{return pow(mod-2);}
	/*mint inv()const{
		int x,y;
		int g=extgcd(v,mod,x,y);
		assert(g==1);
		if(x<0)x+=mod;
		return mint(x);
	}*/
	friend ostream& operator<<(ostream&os,const mint&m){
		return os<<m.v;
	}
	bool operator<(const mint&r)const{return v<r.v;}
	bool operator==(const mint&r)const{return v==r.v;}
};

const int vmax=(1<<21)+10;
mint fact[vmax],finv[vmax],invs[vmax];
void initfact(){
	fact[0]=1;
	rng(i,1,vmax){
		fact[i]=fact[i-1]*i;
	}
	finv[vmax-1]=fact[vmax-1].inv();
	for(int i=vmax-2;i>=0;i--){
		finv[i]=finv[i+1]*(i+1);
	}
	for(int i=vmax-1;i>=1;i--){
		invs[i]=finv[i]*fact[i-1];
	}
}
mint choose(int n,int k){
	return fact[n]*finv[n-k]*finv[k];
}
mint binom(int a,int b){
	return fact[a+b]*finv[a]*finv[b];
}
mint catalan(int n){
	return binom(n,n)-(n-1>=0?binom(n-1,n+1):0);
}

template<class num>
struct Vector{
	vector<num> v;
	Vector(int s=0){
		v.resize(s,num(0));
	}
	int size()const{
		return v.size();
	}
	num& operator[](int i){
		return v[i];
	}
	num const& operator[](int i)const{
		return v[i];
	}
	Vector& operator+=(const Vector&rhs){
		assert(size()==rhs.size());
		rep(i,size())
			v[i]+=rhs[i];
		return *this;
	}
	Vector& operator-=(const Vector&rhs){
		assert(size()==rhs.size());
		rep(i,size())
			v[i]-=rhs[i];
		return *this;
	}
	Vector& operator*=(const num&x){
		rep(i,size())
			v[i]*=x;
		return *this;
	}
	Vector& operator/=(const num&x){
		num y=num(1)/x;
		rep(i,size())
			v[i]*=y;
		return *this;
	}
	Vector operator+(const Vector&rhs)const{
		return Vector(*this)+=rhs;
	}
	Vector operator-(const Vector&rhs)const{
		return Vector(*this)-=rhs;
	}
	Vector operator*(const num&x)const{
		return Vector(*this)*=x;
	}
	Vector operator/(const num&x)const{
		return Vector(*this)/=x;
	}
};

template<class num>
num dot(const Vector<num>&a,const Vector<num>&b){
	assert(a.size()==b.size());
	const int s=a.size();
	num ans=0;
	rep(i,s)
		ans+=a[i]*b[i];
	return ans;
}

template<class num>
struct Matrix{
	using V=Vector<num>;
	vector<V> m;
	Matrix(int s=0,num z=num(0)){
		m.resize(s,V(s));
		rep(i,size())
			m[i][i]=z;
	}
	int size()const{
		return m.size();
	}
	Matrix operator*(const Matrix&rhs)const{
		assert(size()==rhs.size());
		Matrix res(size());
		rep(i,size())rep(j,size())rep(k,size())
			res[i][j]+=m[i][k]*rhs[k][j];
		return res;
	}
	V operator*(const V&rhs)const{
		assert(size()==rhs.size());
		V res(size());
		rep(i,size())
			res[i]=dot(m[i],rhs);
		return res;
	}
	V& operator[](int i){
		return m[i];
	}
	V const& operator[](int i) const{
		return m[i];
	}
};

template<class num>
ostream&operator<<(ostream&os,const Matrix<num>&x){
	const int s=x.size();
	os<<"----------"<<endl;
	rep(i,s){
		rep(j,s){
			os<<x[i][j];
			if(j==s-1){
				os<<endl;
			}else{
				os<<" ";
			}
		}
	}
	return os<<"----------";
}

template<class num>
num det(Matrix<num> a){
	const int s=a.size();
	num ans(1);
	rep(i,s){
		rng(j,i+1,s)if(a[j][i]){
			ans=-ans;
			swap(a[j],a[i]);
			break;
		}
		if(!a[i][i])return 0;
		ans*=a[i][i];
		rng(j,i+1,s){
			mint w=-a[j][i]/a[i][i];
			rng(k,i,s)
				a[j][k]+=a[i][k]*w;
		}
	}
	return ans;
}

using V=Vector<mint>;
using M=Matrix<mint>;

void answer(mint x){
	cout<<x<<endl;
	exit(0);
}

signed main(){
	cin.tie(0);
	ios::sync_with_stdio(0);
	cout<<fixed<<setprecision(20);
	
	initfact();
	
	int h,w,k;cin>>h>>w>>k;
	
	if(k==0){
		answer(1);
	}
	k--;
	
	vvc<int> x(h);
	rep(i,h){
		string s;cin>>s;
		for(auto c:s)
			x[i].pb(c=='#');
	}
	
	int s=0;
	rep(i,h)rep(j,w)s+=x[i][j];
	
	bool hori=0,vert=0;
	rep(i,h)if(x[i][0]&&x[i][w-1]){
		hori=true;
	}
	rep(j,w)if(x[0][j]&&x[h-1][j]){
		vert=true;
	}
	
	if(hori&&vert){
		answer(1);
	}
	if(!hori&&!vert){
		answer(mint(s).pow(k));
	}
	
	if(vert){
		vvc<int> y(w,vi(h));
		rep(i,h)rep(j,w)y[j][i]=x[i][j];
		
		swap(x,y);
		swap(h,w);
	}
	
	int t=0;
	rep(i,h)rep(j,w-1)
		if(x[i][j]&&x[i][j+1])
			t++;
	
	int c=0;
	rep(i,h)if(x[i][0]&&x[i][w-1])
		c++;
	
	dmp(s);
	dmp(t);
	dmp(c);
	
	M z(2);
	z[0][0]=s;
	z[0][1]=-t;
	z[1][1]=c;
	
	V v(2);
	v[0]=1;
	v[1]=1;
	
	while(k){
		if(k%2)v=z*v;
		z=z*z;
		k>>=1;
	}
	
	answer(v[0]);
}


Measured memory_bytes: 40704