/*
このコード、と～おれ!
Be accepted!
∧＿∧　
（｡･ω･｡)つ━☆・*。
⊂　　 ノ 　　　・゜+.
　しーＪ　　　°。+ *´¨)
 　　　　　　　　　.· ´¸.·*´¨) ¸.·*¨)
		  　　　　　　　　　　(¸.·´ (¸.·'* ☆
*/

#include <cstdio>
#include <algorithm>
#include <string>
#include <cmath>
#include <cstring>
#include <vector>
#include <numeric>
#include <iostream>
#include <random>
#include <map>
#include <unordered_map>
#include <queue>
#include <regex>
#include <functional>
#include <complex>
#include <list>
#include <cassert>
#include <iomanip>
#include <set>
#include <stack>
#include <bitset>
#include <array>
#include <chrono>

//#pragma GCC target("arch=skylake-avx512")
//#pragma GCC target("avx2")
//#pragma GCC optimize("O3")
//#pragma GCC optimize("Ofast")
//#pragma GCC target("sse4")
//#pragma GCC optimize("unroll-loops")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#define repeat(i, n, m) for(int i = n; i < (m); ++i)
#define rep(i, n) for(int i = 0; i < (n); ++i)
#define printynl(a) printf(a ? "yes\n" : "no\n")
#define printyn(a) printf(a ? "Yes\n" : "No\n")
#define printYN(a) printf(a ? "YES\n" : "NO\n")
#define printim(a) printf(a ? "possible\n" : "imposible\n")
#define printdb(a) printf("%.50lf\n", a)
#define printLdb(a) printf("%.50Lf\n", a)
#define printdbd(a) printf("%.16lf\n", a)
#define prints(s) printf("%s\n", s.c_str())
#define all(x) (x).begin(), (x).end()
#define deg_to_rad(deg) (((deg)/360.0L)*2.0L*PI)
#define rad_to_deg(rad) (((rad)/2.0L/PI)*360.0L)
#define Please return
#define AC 0
#define manhattan_dist(a, b, c, d) (abs(a - c) + abs(b - d))

using ll = long long;
using ull = unsigned long long;

constexpr int INF = 1073741823;
constexpr int MINF = -1073741823;
constexpr ll LINF = ll(4661686018427387903);
constexpr ll MOD = 1e9 + 7;
constexpr ll mod = 998244353;
constexpr long double eps = 1e-6;
const long double PI = acosl(-1.0L);

using namespace std;

void scans(string& str) {
	char c;
	str = "";
	scanf("%c", &c);
	if (c == '\n')scanf("%c", &c);
	while (c != '\n' && c != -1 && c != ' ') {
		str += c;
		scanf("%c", &c);
	}
}

void scanc(char& str) {
	char c;
	scanf("%c", &c);
	if (c == -1)return;
	while (c == '\n') {
		scanf("%c", &c);
	}
	str = c;
}

double acot(double x) {
	return PI / 2 - atan(x);
}

ll LSB(ll n) { return (n & (-n)); }

template<typename T>
inline T chmin(T& a, const T& b) {
	if (a > b)a = b;
	return a;
}

template<typename T>
inline T chmax(T& a, const T& b) {
	if (a < b)a = b;
	return a;
}

//cpp_int
#if __has_include(<boost/multiprecision/cpp_int.hpp>)
#include <boost/multiprecision/cpp_int.hpp>
#include <boost/multiprecision/cpp_dec_float.hpp>
using namespace boost::multiprecision;
#else
using cpp_int = ll;
#endif

//atcoder library
#if __has_include(<atcoder/all>)
#include <atcoder/all>
//using namespace atcoder;
#endif

/*
	random_device seed_gen;
	mt19937 engine(seed_gen());
	uniform_int_distribution dist(1, 100);
*/


/*----------------------------------------------------------------------------------*/

int dx[4] = { 1, 0, -1, 0 }, dy[4] = { 0, -1, 0, 1 };
set<pair<int, int>> ret;
bool ushi = false;

void dfs(const int &ans, const vector<string> &s, const int &h, const int &w, const int& y, const int& x, const int& cnt, set<pair<int, int>> st) {
	if (ushi)return;
	st.insert({ y, x });
	if (cnt > ans)return;
	if (x == w - 1 and y == h - 1) {
		if (cnt == ans) {
			ret = st;
			ushi = true;
			return;
		}
	}
	rep(i, 4) {
		if (x + dx[i] < w and x + dx[i] >= 0 and y + dy[i] < h and y + dy[i] >= 0 and st.find({ y + dy[i], x + dx[i] }) == st.end()) {
			if(s[y + dy[i]][x + dx[i]] != '#')dfs(ans, s, h, w, y + dy[i], x + dx[i], cnt + 1, st);
		}
	}
}

int main() {

	int h, w, x;
	scanf("%d%d%d", &h, &w, &x);
	vector<string> s(h);
	rep(i, h) {
		rep(j, w) {
			if (i % 2 and j % 2)s[i] += '#';
			else if (i % 2 == 0 and j % 2 == 0)s[i] += '.';
			else s[i] += '?';
		}
	}
	dfs(x, s, h, w, 0, 0, 0, {});
	if (ret.size() == 0) {
		puts("-1");
		return 0;
	}
	rep(i, h) {
		rep(j, w) {
			if (ret.find({ i, j }) != ret.end() or (i % 2 == 0 and j % 2 == 0))s[i][j] = '.';
			else s[i][j] = '#';
		}
	}
	rep(i, h)prints(s[i]);

	Please AC;
}