#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> l_l;
typedef pair<int, int> i_i;
template<class T>
inline bool chmax(T &a, T b) {
    if(a < b) {
        a = b;
        return true;
    }
    return false;
}

template<class T>
inline bool chmin(T &a, T b) {
    if(a > b) {
        a = b;
        return true;
    }
    return false;
}

const ll mod = 1000000007;
ll beki(ll a, ll b) {
    if(b == 0) return 1;
    ll ret = beki(a, b / 2);
    ret = ret * ret % mod;
    if(b & 1) ret = ret * a % mod;
    return ret;
}
template< class T >
struct Matrix {
  vector< vector< T > > A;

  Matrix() {}

  Matrix(size_t n, size_t m) : A(n, vector< T >(m, 0)) {}

  Matrix(size_t n) : A(n, vector< T >(n, 0)) {};

  size_t height() const {
    return (A.size());
  }

  size_t width() const {
    return (A[0].size());
  }

  inline const vector< T > &operator[](int k) const {
    return (A.at(k));
  }

  inline vector< T > &operator[](int k) {
    return (A.at(k));
  }

  static Matrix I(size_t n) {
    Matrix mat(n);
    for(int i = 0; i < n; i++) mat[i][i] = 1;
    return (mat);
  }

  Matrix &operator+=(const Matrix &B) {
    size_t n = height(), m = width();
    assert(n == B.height() && m == B.width());
    for(int i = 0; i < n; i++)
      for(int j = 0; j < m; j++)
        (*this)[i][j] = ((*this)[i][j] + B[i][j]) % mod;
    return (*this);
  }

  Matrix &operator-=(const Matrix &B) {
    size_t n = height(), m = width();
    assert(n == B.height() && m == B.width());
    for(int i = 0; i < n; i++)
      for(int j = 0; j < m; j++)
        (*this)[i][j] = ((*this)[i][j] - B[i][j] + mod) % mod;
    return (*this);
  }

  Matrix &operator*=(const Matrix &B) {
    size_t n = height(), m = B.width(), p = width();
    assert(p == B.height());
    vector< vector< T > > C(n, vector< T >(m, 0));
    for(int i = 0; i < n; i++)
      for(int j = 0; j < m; j++)
        for(int k = 0; k < p; k++)
          C[i][j] = ((C[i][j] + (*this)[i][k] * B[k][j])) % mod;
    A.swap(C);
    return (*this);
  }

  Matrix &operator^=(long long k) {
    Matrix B = Matrix::I(height());
    while(k > 0) {
      if(k & 1) B *= *this;
      *this *= *this;
      k >>= 1LL;
    }
    A.swap(B.A);
    return (*this);
  }

  Matrix operator+(const Matrix &B) const {
    return (Matrix(*this) += B);
  }

  Matrix operator-(const Matrix &B) const {
    return (Matrix(*this) -= B);
  }

  Matrix operator*(const Matrix &B) const {
    return (Matrix(*this) *= B);
  }

  Matrix operator^(const long long k) const {
    return (Matrix(*this) ^= k);
  }

  friend ostream &operator<<(ostream &os, Matrix &p) {
    size_t n = p.height(), m = p.width();
    for(int i = 0; i < n; i++) {
      os << "[";
      for(int j = 0; j < m; j++) {
        os << p[i][j] << (j + 1 == m ? "]\n" : ",");
      }
    }
    return (os);
  }


  T determinant() {
    Matrix B(*this);
    assert(width() == height());
    T ret = 1;
    for(int i = 0; i < width(); i++) {
      int idx = -1;
      for(int j = i; j < width(); j++) {
        if(B[j][i] != 0) idx = j;
      }
      if(idx == -1) return (0);
      if(i != idx) {
        ret *= -1;
        swap(B[i], B[idx]);
      }
      ret *= B[i][i];
      T vv = B[i][i];
      for(int j = 0; j < width(); j++) {
        B[i][j] /= vv;
      }
      for(int j = i + 1; j < width(); j++) {
        T a = B[j][i];
        for(int k = 0; k < width(); k++) {
          B[j][k] -= B[i][k] * a;
        }
      }
    }
    return (ret);
  }
};

ll W, H, K;
string S[1050];
ll num;
bool tate, yoko;
string T[1050];
void rotate() {
    for(int w = 0; w < W; w++) {
        for(int h = 0; h < H; h++) {
            T[w].push_back(S[h][w]);
        }
    }
    for(int w = 0; w < W; w++) {
        S[w] = T[w];
    }
    swap(W, H);
}

int main() {
    //cout.precision(10);
    cin.tie(0);
    ios::sync_with_stdio(false);
    cin >> H >> W >> K;
    for(int i = 0; i < H; i++) {
        cin >> S[i];
        for(int j = 0; j < W; j++) {
            if(S[i][j] == '#') num++;
        }
    }
    for(int i = 0; i < W; i++) {
        if(S[0][i] == '#' && S[H-1][i] == '#') tate = true;
    }
    for(int i = 0; i < H; i++) {
        if(S[i][0] == '#' && S[i][W-1] == '#') yoko = true;
    }
    if(tate && yoko) {
        cout << 1 << endl;
        return 0;
    }
    if(!tate && !yoko) {
        if(K == 0) {
            cout << 1 << endl;
        } else {
            cout << beki(num, K - 1) << endl;
        }
        return 0;
    }
    if(tate) rotate();
    Matrix<ll> A(3);
    Matrix<ll> v(3, 1);
    v[0][0] = 1;
    v[2][0] = 1;
    //v[0][0] = num;
    //v[2][0] = 1;
    A[0][0] = num;
    A[2][0] = 1;
    A[2][1] = mod - 1;
    for(int h = 0; h < H; h++) {
        for(int w = 1; w < W; w++) {
            if(S[h][w] == '#' && S[h][w-1] == '#') {
                //v[1][0]++;
                A[1][0]++;
            }
        }
        if(S[h][0] == '#' && S[h][W-1] == '#') {
            A[1][1]++;
        }
    }
    //cerr << A << endl;
    v = (A ^ K) * v;
    /*
    for(int k = 1; k <= K; k++) {
        v = A * v;
        cerr << v << endl;
    }
    */
    cout << v[2][0] << endl;
    return 0;
}


Measured memory_bytes: 2432