//Practice, Practice, Practice

//#pragma GCC optimize("O3")
//#pragma GCC optimize("unroll-loops")
//#pragma GCC target("avx,avx2,fma")

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>

#define debug(x) cerr << #x << " is " << x << endl;
#define Practice ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define el '\n'
#define pb push_back
#define F first
#define S second
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define ll long long
#define ull unsigned long long
#define one(x) __builtin_popcountll(x)
#define double long double
#define sz(x) x.size()
#define INF 1e9
#define int long long
using namespace std;
using namespace __gnu_pbds;
typedef tree<int,null_type,less<int>,rb_tree_tag, tree_order_statistics_node_update> indexed_set;
const int MAXN = 5e5 + 5, SQ = 350, mod = 1e9 + 7, LOG = 21, base = 37;

void doWork() {
    int n, m, k;
    cin >> n >> m >> k;
    if(n < k)return void (cout << "Impossible" << el);
    for(int i = 0; i < n; ++i){
        for(int j = 0; j < m; ++j){
            if(i == j && k) k--, cout << "*";
            else cout << ".";
        }
        cout << el;
    }
}
int32_t main(){
    Practice
    int testcases = 1;
    //cin >> testcases;
    for(; testcases; testcases--){
        doWork();
    }
    return 0;
}