//@formatter:off
#include<bits/stdc++.h>
#define overload4(_1,_2,_3,_4,name,...) name
#define rep1(i,n) for (ll i = 0; i < ll(n); ++i)
#define rep2(i,s,n) for (ll i = ll(s); i < ll(n); ++i)
#define rep3(i,s,n,d) for(ll i = ll(s); i < ll(n); i+=d)
#define rep(...) overload4(__VA_ARGS__,rep3,rep2,rep1)(__VA_ARGS__)
#define rrep1(i,n) for (ll i = ll(n)-1; i >= 0; i--)
#define rrep2(i,n,t) for (ll i = ll(n)-1; i >= (ll)t; i--)
#define rrep3(i,n,t,d) for (ll i = ll(n)-1; i >= (ll)t; i-=d)
#define rrep(...) overload4(__VA_ARGS__,rrep3,rrep2,rrep1)(__VA_ARGS__)
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define popcount(x) __builtin_popcount(x)
#define pb push_back
#define eb emplace_back
#ifdef __LOCAL
#define debug(...) { cout << #__VA_ARGS__; cout << ": "; print(__VA_ARGS__); cout << flush; }
#else
#define debug(...) void(0)
#endif
#define INT(...) int __VA_ARGS__;scan(__VA_ARGS__)
#define LL(...) ll __VA_ARGS__;scan(__VA_ARGS__)
#define STR(...) string __VA_ARGS__;scan(__VA_ARGS__)
#define CHR(...) char __VA_ARGS__;scan(__VA_ARGS__)
#define DBL(...) double __VA_ARGS__;scan(__VA_ARGS__)
#define LD(...) ld __VA_ARGS__;scan(__VA_ARGS__)
using namespace std;
using ll = long long;
using ld = long double;
using P = pair<int,int>;
using LP = pair<ll,ll>;
using vi = vector<int>;
using vvi = vector<vector<int>>;
using vl = vector<ll>;
using vvl = vector<vector<ll>>;
using vd = vector<double>;
using vvd = vector<vector<double>>;
using vs = vector<string>;
using vc = vector<char>;
using vvc = vector<vector<char>>;
using vb = vector<bool>;
using vvb = vector<vector<bool>>;
using vp = vector<P>;
using vvp = vector<vector<P>>;
template<class S,class T> istream& operator>>(istream &is,pair<S,T> &p) { return is >> p.first >> p.second; }
template<class S,class T> ostream& operator<<(ostream &os,const pair<S,T> &p) { return os<<'{'<<p.first<<","<<p.second<<'}'; }
template<class T> istream& operator>>(istream &is,vector<T> &v) { for(T &t:v){is>>t;} return is; }
template<class T> ostream& operator<<(ostream &os,const vector<T> &v) { os<<'[';rep(i,v.size())os<<v[i]<<(i==int(v.size()-1)?"":","); return os<<']'; }
template<class T> void vecout(const vector<T> &v,char div='\n') { rep(i,v.size()) cout<<v[i]<<(i==int(v.size()-1)?'\n':div);}
template<class T> bool chmin(T& a,T b) {if(a > b){a = b; return true;} return false;}
template<class T> bool chmax(T& a,T b) {if(a < b){a = b; return true;} return false;}
void scan(){}
template <class Head, class... Tail> void scan(Head& head, Tail&... tail){ cin >> head; scan(tail...); }
template<class T> void print(const T& t){ cout << t << '\n'; }
template <class Head, class... Tail> void print(const Head& head, const Tail&... tail){ cout<<head<<' '; print(tail...); }
template<class... T> void fin(const T&... a) { print(a...); exit(0); }
const string yes[] = {"no","yes"};
const string Yes[] = {"No","Yes"};
const string YES[] = {"NO","YES"};
const int inf = 1001001001;
const ll linf = 1001001001001001001;
//@formatter:on

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    cout << boolalpha << fixed << setprecision(15);
    INT(h, w, x);
    if (x & 1) fin(-1);
    int a = (h + 1) / 2, b = (w + 1) / 2;
    rep(_, 1) {
        int mx = (h - 1) + (w - 1) * ((a & 1) ? a : a - 1);
        if (~a & 1) {
            mx += 2 * (b & 1 ? b - 1 : b - 2);
        }
        if (x <= mx) {
            vs ans(h, "");
            rep(i, h) {
                if (i & 1) ans[i] = string(w, '#');
                else ans[i] = string(w, '.');
                ans[i][w - 1] = '.';
            }
            int rem = x - (h - 1) - (w - 1);
            rem /= 2;
            if (rem & 1) continue;
            rep(i, 3, h, 4) {
                if (rem > w - 1) {
                    ans[i][0] = '.';
                    ans[i].back() = '#';
                    rem -= w - 1;
                } else {
                    ans[i][w - 1 - rem] = '.';
                    ans[i].back() = '#';
                    rem = 0;
                    break;
                }
            }
            if (rem > 0) {
                assert(~a & 1);
                assert(~rem & 1);
                rem /= 2;
                rep(j, 0, rem * 4, 4) {
                    assert(j + 2 < w - 1);
                    ans[h - 2][j] = '#';
                    ans[h - 2][j + 2] = '#';
                    ans[h - 1][j] = '#';
                    ans[h - 1][j + 1] = '#';
                    ans[h - 1][j + 2] = '#';
                    ans[h - 3][j + 1] = '.';
                }
            }
            rep(i, h) print(ans[i]);
            return 0;
        }
    }
    rep(_, 1) {
        int mx = (w - 1) + (h - 1) * ((b & 1) ? b : b - 1);
        if (~b & 1) {
            mx += 2 * (a & 1 ? a - 1 : a - 2);
        }
        if (x <= mx) {
            vs ans(h);
            rep(i, h) {
                rep(j, w) {
                    if (j & 1) ans[i].pb('#');
                    else ans[i].pb('.');
                }
            }
            ans[h - 1] = string(w, '.');
            int rem = x - (h - 1) - (w - 1);
            rem /= 2;
            if (rem & 1) continue;
            rep(j, 3, w, 4) {
                if (rem > h - 1) {
                    ans[0][j] = '.';
                    ans[h - 1][j] = '#';
                    rem -= h - 1;
                } else {
                    ans[h - 1 - rem][j] = '.';
                    ans[h - 1][j] = '#';
                    rem = 0;
                    break;
                }
            }
            if (rem > 0) {
                assert(~b & 1);
                assert(~rem & 1);
                rem /= 2;
                rep(i, 0, rem * 4, 4) {
                    assert(i + 2 < h - 1);
                    ans[i][w - 2] = '#';
                    ans[i + 2][w - 2] = '#';
                    ans[i][w - 1] = '#';
                    ans[i + 1][w - 1] = '#';
                    ans[i + 2][w - 1] = '#';
                    ans[i + 1][w - 3] = '.';
                }
            }
            rep(i, h) print(ans[i]);
            return 0;
        }
    }
    fin(-1);
}