// #pragma GCC target("avx2")
#pragma GCC optimize("O3")
// #pragma GCC optimize("unroll-loops")
#include<bits/stdc++.h>
// #include<sys/time.h>
// #include<atcoder/modint>

using namespace std;

// using mint = atcoder::modint998244353;

using P = pair<int, int>;

const int M = 998244353;
const long long LM = 1LL << 60;


vector<string> solve(int h, int w, int k) {
    if (k == 0) {
        return vector<string>(h, string(w, '.'));
    }
    if (h == 1 || w == 1) {
        if (k == 1) {
            vector<string> tmp(h, string(w, '.'));
            tmp[0][0] = '#';
            return tmp;
        }
        else {
            return {};
        }
    }
    assert(h >= 2 && w >= 2);
    if (k == 1) {
        return {};
    }
    assert(h >= 2 && w >= 2 && k >= 2);

    if (k < h + w - 1) {
        int ci = min(k - 1, h - 1);
        int cj = k - ci;
        vector<string> tmp(h, string(w, '.'));
        for (int i = 0; i < ci; ++i) {
            for (int j = 0; j < cj; ++j) {
                tmp[i][j] = '#';
            }
        }
        return tmp;
    }
    for (int sw = 0; sw < 2; ++sw) {
        vector<string> b(h, string(w, '.'));
        for (int j = 0; j < w; ++j) {
            b[0][j] = '#';
        }
        int rem = k - w;
        int si = 1;
        int lim = w - 1;
        for (; si < h - 1 && rem % 2 == 1; ++si) {
            if (rem >= 1) {
                lim = w - 2;
                b[si][w - 1] = '#';
                rem -= 1;
            }
        }
        for (int j = 1; j < lim; j += 2) {
            for (int i = 1; i < h - 1; ++i) {
                if (rem >= 2) {
                    b[i][j] = '#';
                    rem -= 2;
                }
            }
        }
        for (; si < h - 1; ++si) {
            if (rem >= 1) {
                b[si][w - 1] = '#';
                rem -= 1;
            }
        }
        if (rem == 0) {
            if (sw) {
                vector<string> tmp(w, string(h, '.'));
                for (int i = 0; i < h; ++i) {
                    for (int j = 0; j < w; ++j) {
                        tmp[j][i] = b[i][j];
                    }
                }
                swap(b, tmp);
            }
            return b;
        }
    }
    return {};

}


int main() {
    cin.tie(0);
    ios::sync_with_stdio(0);
    int h, w, k;
    cin >> h >> w >> k;
    auto b = solve(h, w, k);
    // cout << b.size() << '\n';
    if (b.empty()) {
        cout << -1 << '\n';
        return 0;
    }
    for (auto&& i : b) {
        cout << i << '\n';
    }
    return 0;
}