#define DEB
#include<bits/stdc++.h>
#define REP(i,m) for(int i=0;i<(m);++i)
#define REPN(i,m,in) for(int i=(in);i<(m);++i)
#define ALL(t) (t).begin(),(t).end()
#define CLR(a) memset((a),0,sizeof(a))
#define pb push_back
#define mp make_pair
#define fr first
#define sc second

using namespace std;


#ifdef DEB
#define dump(x)  cerr << #x << " = " << (x) << endl
#define prl cerr<<"called:"<< __LINE__<<endl
template<class T> void 
debug(T a,T b){ for(;a!=b;++a) cerr<<*a<<' ';cerr<<endl;}
#else
#define dump(x) ;
#define prl ;
template<class T> void debug(T a,T b){ ;}
#endif

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

typedef long long int lint;
typedef pair<int,int> pi;

namespace std{
  template<class S,class T>
  ostream &operator <<(ostream& out,const pair<S,T>& a){
    out<<'('<<a.fr<<','<<a.sc<<')';
    return out;
  }
}


template<lint mod>
struct Int_{
  unsigned x;
  unsigned mpow(Int_ a,unsigned k){
    Int_ res=1;
    while(k){
      if(k&1) res=res*a;
      a=a*a;
      k>>=1;
    }
    return res.x;
  }
  unsigned inverse(Int_ a){
    return mpow(a,mod-2);
  }
  Int_(): x(0) { }
  Int_(long long sig) {
    int sigt=sig%mod;
    if(sigt<0) sigt+=mod;
    x=sigt;
  }
  unsigned get() const { return (unsigned)x; }
  
  Int_ &operator+=(Int_ that) { if((x += that.x) >= mod) x -= mod; return *this; }
  Int_ &operator-=(Int_ that) { if((x += mod - that.x) >= mod) x -= mod; return *this; }
  Int_ &operator*=(Int_ that) { x = (unsigned long long)x * that.x % mod; return *this; }
  Int_ &operator=(Int_ that) { x=that.x; return *this;}
  Int_ &operator/=(Int_ that) { x=(unsigned long long) x * inverse(that.x)%mod; return *this;}
  bool operator==(Int_ that) const { return x==that.x; }
  bool operator!=(Int_ that) const { return x!=that.x; }

  Int_ operator-() const { return Int_(0)-Int_(*this);}
  Int_ operator+(Int_ that) const { return Int_(*this) += that; }
  Int_ operator-(Int_ that) const { return Int_(*this) -= that; }
  Int_ operator*(Int_ that) const { return Int_(*this) *= that; }
  Int_ operator/(Int_ that) const { return Int_(*this) /= that; }

};

namespace std{
  template<lint mod>
  ostream &operator <<(ostream& out,const Int_<mod>& a){
    out<<a.get();
    return out;
  }
  template<lint mod>
  istream &operator >>(istream& in,Int_<mod>& a){
    in>>a.x;
    return in;
  }
};

typedef Int_<1000000007> Int;

Int mpow(Int a,lint k){
  Int res=1;
  while(k){
    if(k&1) res=res*a;
    a=a*a;
    k>>=1;
  }
  return res;
}

//const int INF=5e8;
char buf[2005][2005],nbuf[2005][2005];
char s[1005][1005],s2[1005][1005];
int h,w;
lint K;

int main(){
  cin>>h>>w>>K;
  REP(i,h) scanf("%s",s[i]);

  int b=0;
  REP(i,h) REP(j,w) if(s[i][j]=='#') ++b;

  int tate=0,yoko=0;
  REP(i,h) if(s[i][0]=='#' && s[i][w-1]=='#') yoko++;
  REP(i,w) if(s[0][i]=='#' && s[h-1][i]=='#') tate++;
  if(K==0 || K==1){
    puts("1");
    return 0;
  }
  --K;
  if(tate&&yoko){
    puts("1");
    return 0;
  }
  if(!tate && !yoko){
    cout<<mpow(b,K)<<endl;
    return 0;
  }
  if(tate && !yoko){
    REP(i,h) REP(j,w) s2[j][i]=s[i][j];
    swap(h,w);
    REP(i,h) REP(j,w) s[i][j]=s2[i][j];
    swap(tate,yoko);
  }

  int adj=0;
  REP(i,h) REP(j,w-1) if(s[i][j]=='#' && s[i][j+1]=='#') ++adj;


  Int res=mpow(b,K);
  Int x=Int(b)/yoko,y=yoko;
  Int subt;
  if(x.x!=1) subt=((mpow(x,K)-1)/(x-1));
  else subt=K;
  subt*=mpow(y,K-1)*adj;

  res-=subt;
  cout<<res<<endl;

/*
  int h2=1,w2=1;
  buf[0][0]='#';
  REP(_,K){
    int h3=h2*h,w3=w*w2;
    REP(i,h3) REP(j,w3) nbuf[i][j]='.';
    REP(i,h2) REP(j,w2) if(buf[i][j]=='#'){
      REP(i2,h) REP(j2,w) if(s[i2][j2]=='#') nbuf[i*h+i2][j*w+j2]='#';
    }
    h2=h3;
    w2=w3;
    memcpy(buf,nbuf,sizeof(nbuf));
  }
  dump(solve(h2,w2));
*/


  return 0;
}





Measured memory_bytes: 2176