#include <iostream>
#include <bitset>
#include <random>
#include <chrono>
#include <iomanip>
#include <set>
#include <map>
#include <queue>
#include <deque>
#include <string>
#include <stack>
#include <ranges>
#include <algorithm>
#include <vector>
using namespace std;
using ll=long long;

#include <atcoder/all>
using mint=atcoder::modint998244353;

ostream& operator<<(ostream& os,const mint& x){
	os<<x.val();
	return os;
}
istream& operator>>(istream& is,mint& x){
	int t;
	is>>t;
	x=t;
	return is;
}

template <typename S,typename T>
ostream& operator<<(ostream& os,const pair<S,T>& p);
template <typename S,typename T>
istream& operator>>(istream& is,pair<S,T>& p);
template <typename T,size_t n>
ostream& operator<<(ostream& os,const array<T,n>& arr);
template <typename T,size_t n>
istream& operator>>(istream& is,array<T,n>& arr);
template <typename T>
ostream& operator<<(ostream& os,const vector<T>& vec);
template <typename T>
istream& operator>>(istream& is,vector<T>& vec);

template <typename S,typename T>
ostream& operator<<(ostream& os,const pair<S,T>& p){
	os<<p.first<<" "<<p.second;
	return os;
}
template <typename S,typename T>
istream& operator>>(istream& is,pair<S,T>& p){
	is>>p.first>>p.second;
	return is;
}

template <typename T,size_t n>
ostream& operator<<(ostream& os,const array<T,n>& arr){
	for(int i=0;i<n;i++)os<<arr[i]<<(i+1==n?"":" ");
	return os;
}
template <typename T,size_t n>
istream& operator>>(istream& is,array<T,n>& arr){
	for(int i=0;i<n;i++)is>>arr[i];
	return is;
}
template <typename T>
ostream& operator<<(ostream& os,const vector<T>& vec){
	for(int i=0;i<(int)vec.size();i++)os<<vec[i]<<(i+1==(int)vec.size()?"":" ");
	return os;
}
template <typename T>
istream& operator>>(istream& is,vector<T>& vec){
	for(int i=0;i<(int)vec.size();i++)is>>vec[i];
	return is;
}

template<class... Vecs>
void input_vec(Vecs&... vs) {
    const auto n = get<0>(tie(vs...)).size();

    for (size_t i = 0; i < n; ++i)
        ((cin >> vs[i]), ...);
}

template <class... Vecs>
void output_vec(const Vecs&... vs) {
    const auto n = get<0>(tie(vs...)).size();

    for (size_t i = 0; i < n; ++i) {
        bool first = true;
        (((cout << (exchange(first, false) ? "" : " ") << vs[i])), ...);
        cout << endl;
    }
}

template <typename T>
vector<T> make_unique(vector<T> vec){
	ranges::sort(vec);
	vec.erase(unique(vec.begin(),vec.end()),vec.end());
	return vec;
}

vector<int> Iota(int n,int s=0){
	vector<int> res(n);
	iota(res.begin(),res.end(),s);
	return res;
}

vector<ll> Iotall(int n,ll s=0){
	vector<ll> res(n);
	iota(res.begin(),res.end(),s);
	return res;
}
void YESNO(bool f){
	if(f)cout<<"Yes"<<endl;
	else cout<<"No"<<endl;
}

using vl=vector<ll>;
using vvl=vector<vector<ll>>;
using vvvl=vector<vector<vector<ll>>>; 
using vi=vector<int>;
using vvi=vector<vector<int>>;
using vvvi=vector<vector<vector<int>>>;
vector<string> transpose(vector<string>& s){
	vector<string> res(s[0].size());
	for(int i=0;i<s.size();i++){
		for(int j=0;j<s[i].size();j++)res[j]+=s[i][j];
	}
	return res;
}
int main(){
	cin.tie(nullptr);
	ios::sync_with_stdio(false);
	cout<<fixed<<setprecision(10);
	int h,w,k;
	cin>>h>>w>>k;
	if(k==0){
		for(int i=0;i<h;i++)cout<<string(w,'.')<<endl;
		return 0;
	}
	bool tr=false;
	if(h<w){
		tr=true;
		swap(h,w);
	}
	if(w==1){
		if(k==1){
			vector<string> ans(h,".");
			ans[0]="#";
			if(tr){
				ans=transpose(ans);
				swap(h,w);
			}
			for(int i=0;i<h;i++)cout<<ans[i]<<endl;
		}else cout<<-1<<endl;
		return 0;
	}else{
		if(k==1){
			cout<<-1<<endl;
			return 0;
		}
		vector<string> ans(h,string(w,'.'));
		if(k<=h){
			for(int i=0;i<k-1;i++)ans[i][0]='#';
		}else{
			if(k>(h-1)*(w-1)+1){
				cout<<-1<<endl;
				return 0;
			}
			vi d(h);
			d[0]=1;
			k-=h;
			for(int i=1;i<h;i++){
				if(k==0)d[i]=d[i-1];
				else if(d[i-1]==1){
					if(k>=w-2){
						d[i]=w-1;
						k-=w-2;
					}else{
						d[i]=1+k;
						k=0;
					}
				}else{
					if(k>=w-2){
						d[i]=1;
						k-=w-2;
					}else{
						d[i]=w-1-k;
						k=0;
					}
				}
			}
			for(int i=0;i<h;i++){
				for(int j=0;j<d[i];j++)ans[i][j]='#';
			}
		}
		if(tr){
			ans=transpose(ans);
			swap(h,w);
		}
		for(auto x:ans)cout<<x<<endl;
	}
}