#include <bits/stdc++.h>
using namespace std;
using lint = long long int;
using pint = pair<int, int>;
using plint = pair<lint, lint>;
struct fast_ios { fast_ios(){ cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;
#define FOR(i, begin, end) for(int i=(begin),i##_end_=(end);i<i##_end_;i++)
#define IFOR(i, begin, end) for(int i=(end)-1,i##_begin_=(begin);i>=i##_begin_;i--)
#define REP(i, n) FOR(i,0,n)
#define IREP(i, n) IFOR(i,0,n)
template<typename T> istream &operator>>(istream &is, vector<T> &vec){ for (auto &v : vec) is >> v; return is; }
template<typename T> ostream &operator<<(ostream &os, const vector<T> &vec){ os << "["; for (auto v : vec) os << v << ","; os << "]"; return os; }
template<typename T> ostream &operator<<(ostream &os, const deque<T> &vec){ os << "deq["; for (auto v : vec) os << v << ","; os << "]"; return os; }
template<typename T> ostream &operator<<(ostream &os, const set<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const unordered_set<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const multiset<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const unordered_multiset<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &pa){ os << "(" << pa.first << "," << pa.second << ")"; return os; }
template<typename TK, typename TV> ostream &operator<<(ostream &os, const map<TK, TV> &mp){ os << "{"; for (auto v : mp) os << v.first << "=>" << v.second << ","; os << "}"; return os; }
template<typename TK, typename TV> ostream &operator<<(ostream &os, const unordered_map<TK, TV> &mp){ os << "{"; for (auto v : mp) os << v.first << "=>" << v.second << ","; os << "}"; return os; }
template<typename T> void ndarray(vector<T> &vec, int len) { vec.resize(len); }
template<typename T, typename... Args> void ndarray(vector<T> &vec, int len, Args... args) { vec.resize(len); for (auto &v : vec) ndarray(v, args...); }
template<typename T> void Max(T &m, const T q) { if (m < q) m = q; }
template<typename T> void Min(T &m, const T q) { if (m > q) m = q; }
template<typename T1, typename T2> pair<T1, T2> operator+(pair<T1, T2> &l, pair<T1, T2> &r) { return make_pair(l.first + r.first, l.second + r.second); }
template<typename T1, typename T2> pair<T1, T2> operator-(pair<T1, T2> &l, pair<T1, T2> &r) { return make_pair(l.first - r.first, l.second - r.second); }
#define dbg(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ") " << __FILE__ << endl;

int H, W;
lint K;
vector<string> s;
constexpr lint MOD = 1000000007;

lint power(lint x, lint n, lint MOD)
{
    lint ans = 1;
    while (n>0)
    {
        if (n & 1) (ans *= x) %= MOD;
        (x *= x) %= MOD;
       n >>= 1;
    }
   return ans;
}
struct Matrix
{
    using vec = std::vector<lint>;
    using mat = std::vector<vec>;
    mat X;
    lint MOD;

    static mat mul(const mat &A, const mat &B, lint M)
    {
        unsigned H = A.size(), W = B[0].size(), K = B.size();
        mat C(H, vec(W));
        REP(i, H) REP(j, W)
        {
            REP(k, K) (C[i][j] += A[i][k] * B[k][j]) %= M;
            C[i][j] += (C[i][j] < 0) ? M : 0;
        }
        return C;
    }

    Matrix(const mat &matrix, lint mod) : X(matrix), MOD(mod)
    {
        for (auto &vec : X) for (auto &val : vec)
        {
            val = (val % MOD + MOD);
            val = (val >= MOD) ? val - MOD : val;
        }
    }

    Matrix power(lint n)
    {
        int m = X.size();
        mat B(m, vec(m));
        mat C = X;
        REP(i, m) B[i][i] = 1;
        while (n > 0)
        {
            if (n & 1) B = mul(B, C, MOD);
            C = mul(C, C, MOD);
            n >>= 1;
        }
        return Matrix(B, MOD);
    }

    vec dot(const vec &v)
    {
        vec ans(X.size());
        REP(i, X.size()) REP(j, v.size())
        {
            (ans[i] += X[i][j] * v[j]) %= MOD;
        }
        for (auto &v : ans) v += (v < 0) ? MOD : 0;
        return ans;
    }
};

lint kuro;
lint solve(int H, int W, vector<string> s)
{
    lint con = 0, yoko = 0;
    REP(h, H) if (s[h][0] == '#' and s[h][W - 1] == '#') con++;
    REP(h, H) REP(w, W - 1) if (s[h][w] == '#' and s[h][w + 1] == '#') yoko++;
    // 横にはつながっている状況・縦には切れている
    vector<vector<lint>> trans{
        {kuro, MOD - yoko},
        {0, con}};
    Matrix M1(trans, MOD);
    vector<lint> st{1, 1};
    st = M1.power(K - 1).dot(st);
    return st[0];
}

vector<bool> conn(2);
int main()
{
    cin >> H >> W >> K;
    s.resize(H);
    REP(h, H) cin >> s[h];
    kuro = 0;
    for (auto vec : s) for (auto v : vec) kuro += (v == '#');

    REP(w, W) if (s[0][w] == '#' and s[H - 1][w] == '#') conn[0] = true; // 縦にならべてつながるか
    REP(h, H) if (s[h][0] == '#' and s[h][W - 1] == '#') conn[1] = true; // 横にならべてつながるか

    if (K <= 1 or (conn[0] and conn[1]))
    {
        puts("1");
        return 0;
    }
    if (!conn[0] and !conn[1])
    {
        cout << power(kuro, K - 1, MOD) << endl;
        return 0;
    }

    vector<string> sT(W);
    REP(w, W) REP(h, H) sT[w].push_back(s[h][w]);

    // 横にはつながるとして解く
    if (conn[1]) cout << solve(H, W, s) << endl;
    else cout << solve(W, H, sT) << endl;
}


Measured memory_bytes: 3456