#include<bits/stdc++.h>

typedef unsigned int uint;
typedef long long ll;
typedef unsigned long long ull;
typedef double lf;
typedef long double llf;
typedef std::pair<int,int> pii;

#define xx first
#define yy second

template<typename T> inline T max(T a,T b){return a>b?a:b;}
template<typename T> inline T min(T a,T b){return a<b?a:b;}
template<typename T> inline T abs(T a){return a>0?a:-a;}
template<typename T> inline bool repr(T &a,T b){return a<b?a=b,1:0;}
template<typename T> inline bool repl(T &a,T b){return a>b?a=b,1:0;}
template<typename T> inline T gcd(T a,T b){T t;if(a<b){while(a){t=a;a=b%a;b=t;}return b;}else{while(b){t=b;b=a%b;a=t;}return a;}}
template<typename T> inline T sqr(T x){return x*x;}
#define mp(a,b) std::make_pair(a,b)
#define pb push_back
#define I inline
#define mset(a,b) memset(a,b,sizeof(a))
#define mcpy(a,b) memcpy(a,b,sizeof(a))

#define fo0(i,n) for(int i=0,i##end=n;i<i##end;i++)
#define fo1(i,n) for(int i=1,i##end=n;i<=i##end;i++)
#define fo(i,a,b) for(int i=a,i##end=b;i<=i##end;i++)
#define fd0(i,n) for(int i=(n)-1;~i;i--)
#define fd1(i,n) for(int i=n;i;i--)
#define fd(i,a,b) for(int i=a,i##end=b;i>=i##end;i--)
#define foe(i,x)for(__typeof((x).end())i=(x).begin();i!=(x).end();++i)

struct Cg{I char operator()(){return getchar();}};
struct Cp{I void operator()(char x){putchar(x);}};
#define OP operator
#define RT return *this;
#define RX x=0;char t=P();while((t<'0'||t>'9')&&t!='-')t=P();bool f=0;\
if(t=='-')t=P(),f=1;x=t-'0';for(t=P();t>='0'&&t<='9';t=P())x=x*10+t-'0'
#define RL if(t=='.'){lf u=0.1;for(t=P();t>='0'&&t<='9';t=P(),u*=0.1)x+=u*(t-'0');}if(f)x=-x
#define RU x=0;char t=P();while(t<'0'||t>'9')t=P();x=t-'0';for(t=P();t>='0'&&t<='9';t=P())x=x*10+t-'0'
#define TR *this,x;return x;
I bool IS(char x){return x==10||x==13||x==' ';}template<typename T>struct Fr{T P;I Fr&OP,(int&x)
{RX;if(f)x=-x;RT}I OP int(){int x;TR}I Fr&OP,(ll &x){RX;if(f)x=-x;RT}I OP ll(){ll x;TR}I Fr&OP,(char&x)
{for(x=P();IS(x);x=P());RT}I OP char(){char x;TR}I Fr&OP,(char*x){char t=P();for(;IS(t);t=P());if(~t){for(;!IS
(t)&&~t;t=P())*x++=t;}*x++=0;RT}I Fr&OP,(lf&x){RX;RL;RT}I OP lf(){lf x;TR}I Fr&OP,(llf&x){RX;RL;RT}I OP llf()
{llf x;TR}I Fr&OP,(uint&x){RU;RT}I OP uint(){uint x;TR}I Fr&OP,(ull&x){RU;RT}I OP ull(){ull x;TR}};Fr<Cg>in;
#define WI(S) if(x){if(x<0)P('-'),x=-x;char s[S],c=0;while(x)s[c++]=x%10+'0',x/=10;while(c--)P(s[c]);}else P('0')
#define WL if(y){lf t=0.5;for(int i=y;i--;)t*=0.1;if(x>=0)x+=t;else x-=t,P('-');*this,(ll)(abs(x));P('.');if(x<0)\
x=-x;while(y--){x*=10;x-=floor(x*0.1)*10;P(((int)x)%10+'0');}}else if(x>=0)*this,(ll)(x+0.5);else *this,(ll)(x-0.5);
#define WU(S) if(x){char s[S],c=0;while(x)s[c++]=x%10+'0',x/=10;while(c--)P(s[c]);}else P('0')
template<typename T>struct Fw{T P;I Fw&OP,(int x){WI(10);RT}I Fw&OP()(int x){WI(10);RT}I Fw&OP,(uint x){WU(10);RT}
I Fw&OP()(uint x){WU(10);RT}I Fw&OP,(ll x){WI(19);RT}I Fw&OP()(ll x){WI(19);RT}I Fw&OP,(ull x){WU(20);RT}I Fw&OP()
(ull x){WU(20);RT}I Fw&OP,(char x){P(x);RT}I Fw&OP()(char x){P(x);RT}I Fw&OP,(const char*x){while(*x)P(*x++);RT}
I Fw&OP()(const char*x){while(*x)P(*x++);RT}I Fw&OP()(lf x,int y){WL;RT}I Fw&OP()(llf x,int y){WL;RT}};Fw<Cp>out;

const int N=1007,P=1000000007;

char s[N][N];
int n,m;
ll K;

inline int pow(int a,ll b)
{
	int r=1;
	for(;b;b>>=1,a=(ll)a*a%P)
		if(b&1)r=(ll)r*a%P;
	return r;
}

int main()
{
	in,n,m,K;
	fo1(i,n)in,s[i]+1;
	bool ud=0,lr=0;
	fo1(i,n)lr|=s[i][1]=='#'&&s[i][m]=='#';
	fo1(i,m)ud|=s[1][i]=='#'&&s[n][i]=='#';
	//out,lr,' ',ud,'\n';
	if(ud&&lr)return puts("1"),0;
	int a=0,b=0,c=0;
	fo1(i,n)fo1(j,m)a+=s[i][j]=='#';
	if(!ud&&!lr){out,pow(a,K-1),'\n';return 0;}
	if(lr)
	{
		fo1(i,n)fo1(j,m-1)b+=s[i][j]=='#'&&s[i][j+1]=='#';
		fo1(i,n)c+=s[i][1]=='#'&&s[i][m]=='#';
	}
	else
	{
		fo1(i,n-1)fo1(j,m)b+=s[i][j]=='#'&&s[i+1][j]=='#';
		fo1(i,m)c+=s[1][i]=='#'&&s[n][i]=='#';
	}
	//out,a,' ',b,' ',c,'\n';
	int t[4]={1,0,0,1},p[4]={a,0,P-b,c},r[4];
	auto mul=[&](int*a,int*b)
	{
		r[0]=((ll)a[0]*b[0]+(ll)a[1]*b[2])%P;
		r[1]=((ll)a[0]*b[1]+(ll)a[1]*b[3])%P;
		r[2]=((ll)a[2]*b[0]+(ll)a[3]*b[2])%P;
		r[3]=((ll)a[2]*b[1]+(ll)a[3]*b[3])%P;
		a[0]=r[0],a[1]=r[1],a[2]=r[2],a[3]=r[3];
	};
	for(K--;K;K>>=1)
	{
		//fo0(i,4)out,p[i],' ';out,'\n';
		if(K&1)mul(t,p);
		if(K>>1)mul(p,p);
	}
	out,(t[0]+t[2])%P,'\n';
}

Measured memory_bytes: 1280