#include <bits/stdc++.h>
using namespace std;
#define incII(i, l, r) for(decay_t<decltype(r)> i = (l)    ; i <= (r); i++)
#define incIX(i, l, r) for(decay_t<decltype(r)> i = (l)    ; i <  (r); i++)
#define incXI(i, l, r) for(decay_t<decltype(r)> i = (l) + 1; i <= (r); i++)
#define incXX(i, l, r) for(decay_t<decltype(r)> i = (l) + 1; i <  (r); i++)
#define decII(i, l, r) for(decay_t<decltype(r)> i = (r)    ; i >= (l); i--)
#define decIX(i, l, r) for(decay_t<decltype(r)> i = (r) - 1; i >= (l); i--)
#define decXI(i, l, r) for(decay_t<decltype(r)> i = (r)    ; i >  (l); i--)
#define decXX(i, l, r) for(decay_t<decltype(r)> i = (r) - 1; i >  (l); i--)
#define inc(i, n)  incIX(i, 0, n)
#define dec(i, n)  decIX(i, 0, n)
#define inc1(i, n) incII(i, 1, n)
#define dec1(i, n) decII(i, 1, n)
auto inII = [](auto a, auto l, auto r) -> bool { return (l <= a && a <= r); };
auto inIX = [](auto a, auto l, auto r) -> bool { return (l <= a && a <  r); };
auto inXI = [](auto a, auto l, auto r) -> bool { return (l <  a && a <= r); };
auto inXX = [](auto a, auto l, auto r) -> bool { return (l <  a && a <  r); };
auto setmin   = [](auto & a, auto b) -> bool { return (b <  a ? a = b, true : false); };
auto setmax   = [](auto & a, auto b) -> bool { return (b >  a ? a = b, true : false); };
auto setmineq = [](auto & a, auto b) -> bool { return (b <= a ? a = b, true : false); };
auto setmaxeq = [](auto & a, auto b) -> bool { return (b >= a ? a = b, true : false); };
using LL = long long int;
using LD = long double;
#define PB push_back
#define EB emplace_back
#define MP make_pair
#define MT make_tuple
#define FI first
#define SE second
#define FR front()
#define BA back()
#define ALL(a) begin(a), end(a)
#define RALL(a) rbegin(a), rend(a)
#define RV(a) reverse(ALL(a))
#define ST(a) sort(ALL(a))
#define RST(a) sort(RALL(a))
#define SC static_cast
#define SI(a) SC<int>(a.size())
#define SL(a) SC<LL>(a.size())
#define RF(e, ...) for(auto && e: __VA_ARGS__)
#define SF(a, ...) for(auto && [__VA_ARGS__]: a)
#define until(...) while(not(__VA_ARGS__))
#define if_not(...) if(not(__VA_ARGS__))
#define ef else if
#define UR assert(false)
template<typename A>             istream & operator>>(istream & is, vector<A>          & v);
template<typename A>             ostream & operator<<(ostream & os, vector<A>    const & v);
template<typename A, size_t N>   istream & operator>>(istream & is, array<A, N>        & a);
template<typename A, size_t N>   ostream & operator<<(ostream & os, array<A, N>  const & a);
template<typename A, typename B> istream & operator>>(istream & is, pair<A, B>         & p);
template<typename A, typename B> ostream & operator<<(ostream & os, pair<A, B>   const & p);
template<typename ... A>         istream & operator>>(istream & is, tuple<A ...>       & t);
template<typename ... A>         ostream & operator<<(ostream & os, tuple<A ...> const & t);
template<int I = 0, typename T> void tin_ (istream & is, T       & t) { if constexpr(I < tuple_size<T>::value) { is >> get<I>(t); tin_<I + 1>(is, t); } }
template<int I = 0, typename T> void tout_(ostream & os, T const & t) { if constexpr(I < tuple_size<T>::value) { if(I != 0) { os << " "; } os << get<I>(t); tout_<I + 1>(os, t); } }
template<typename A>             istream & operator>>(istream & is, vector<A>          & v) { for(auto && e: v) { is >> e; } return is; }
template<typename A>             ostream & operator<<(ostream & os, vector<A>    const & v) { string ss; for(auto && e: v) { os << ss << e; ss = " "; } return os; }
template<typename A, size_t N>   istream & operator>>(istream & is, array<A, N>        & a) { for(auto && e: a) { is >> e; } return is; }
template<typename A, size_t N>   ostream & operator<<(ostream & os, array<A, N>  const & a) { string ss; for(auto && e: a) { os << ss << e; ss = " "; } return os; }
template<typename A, typename B> istream & operator>>(istream & is, pair<A, B>         & p) { return is >> p.first >> p.second; }
template<typename A, typename B> ostream & operator<<(ostream & os, pair<A, B>   const & p) { return os << p.first << " " << p.second; }
template<typename ... A>         istream & operator>>(istream & is, tuple<A ...>       & t) { tin_ (is, t); return is; }
template<typename ... A>         ostream & operator<<(ostream & os, tuple<A ...> const & t) { tout_(os, t); return os; }
auto * IS = & cin;
auto * OS = & cout;
template<typename ... A> void in(A & ... a) { (* IS >> ... >> a); }
#define IN(...) __VA_ARGS__; in(__VA_ARGS__)
template<typename A                > auto make_v(A a) { return a; }
template<typename A, typename ... M> auto make_v(A a, int n, M ... m) { return vector(n, make_v(a, m ...)); }
template<typename A, typename ... N> auto read_v(N ... n) { auto a = make_v(A { }, n ...); in(a); return a; }
void                                      out_([[maybe_unused]] string const & s) { }
template<typename A                > void out_([[maybe_unused]] string const & s, A const & a) { * OS << a; }
template<typename A, typename ... B> void out_(                 string const & s, A const & a, B const & ... b) { * OS << a << s; out_(s, b ...); }
auto outF  = [](string const & s, string const & t, auto const & ... a) { out_(s, a ...); * OS << t << flush; };
auto outN  = [](auto const & ... a) { outF(""  , ""  , a ...); };
auto outS  = [](auto const & ... a) { outF(" " , " " , a ...); };
auto outL  = [](auto const & ... a) { outF("\n", "\n", a ...); };
auto outSN = [](auto const & ... a) { outF(" " , ""  , a ...); };
auto outNL = [](auto const & ... a) { outF(""  , "\n", a ...); };
auto outSL = [](auto const & ... a) { outF(" " , "\n", a ...); };
auto out   = outSL;
template<typename A                > void disp_(A const & a) { * OS << a; }
template<typename A, typename ... T> void disp_(A const & a, string const & s, T const & ... t) { string ss; for(auto && e: a) { * OS << ss; ss = s; disp_(e, t ...); } }
auto dispI = [](auto const & a, auto const & s, auto const & ... t) { disp_(a, t ...); * OS << s << flush; };
auto dispT = [](auto const & a, auto const & s, auto const & ... t) { for(auto && e: a) { disp_(e, t ...); * OS << s; } * OS << flush; };
auto dispL = [](auto const & a,                 auto const & ... t) { dispT(a, "\n", t ...); };
struct OS_init { OS_init() { * OS << boolalpha << fixed << setprecision(20); } } os_init_;

// ---- ----

auto fl = [](auto a, auto b) { assert(b != 0); return a / b - (a % b != 0 && ((a >= 0) != (b >= 0)) ? 1 : 0); };
auto ce = [](auto a, auto b) { assert(b != 0); return a / b + (a % b != 0 && ((a >= 0) == (b >= 0)) ? 1 : 0); };
auto mo = [](auto a, auto b) { assert(b != 0); a %= b; if(a < 0) { a += abs(b); } return a; };

int main() {
	auto no = [] { out(-1); exit(0); };
	
	int IN(H, W, X);
	int hh = ce(H, 2);
	int ww = ce(W, 2);
	int c = (hh * ww - (hh % 2 == 0 && ww % 2 == 0 ? 1 : 0)) * 2 - 2;
	c -= X;
	if_not(c >= 0 && c % 4 == 0) { no(); }
	c /= 4;
	
	vector<string> ans;
	auto f = [&] {
		if(c == 0) {
			dispL(ans);
			exit(0);
		}
	};
	
	inc(i, H / 4) {
		string s(W, '.'), t(W, '#'), u = t;
		t.BA = '.';
		u.FR = '.';
		ans.PB(s);
		ans.PB(t);
		ans.PB(s);
		ans.PB(u);
	}
	if(H % 4 == 1) {
		ans.PB(string(W, '.'));
	} else {
		string s(W, '.'), t = s, u = s;
		inc(j, W) {
			if(j % 4 == 1) { s[j] = '#'; }
			if(j % 2 == 1) { t[j] = '#'; }
			if(j % 4 == 3) { u[j] = '#'; }
		}
		inc(j, W) {
			if(c > 0 && u[j] == '#') { swap(u[j], s[j]); c--; }
		}
		ans.PB(s);
		ans.PB(t);
		ans.PB(u);
	}
	f();
	
	inc(i, H / 4 * 4) {
		if_not(i % 4 == 1) { continue; }
		dec(j, W) {
			if(j % 2 == 0) { continue; }
			swap(ans[i][j + 1], ans[i][j - 1]);
			c--;
			f();
		}
	}
	no();
}