#include<bits/stdc++.h>
using namespace std;
using ll = long long;

int main(){
    ll h,w;
    cin>>h>>w;
    ll k;
    cin>>k;
    vector<vector<vector<int>>> vis(4,vector<vector<int>>(h,vector<int>(w,-1)));
    int now = 0;
    vector<vector<int>> ans(h,vector<int>(w,0));
    int ni = 0;
    int nj = 0;
    int dx = 1;
    int dy = 1;

    stack<pair<int,pair<int,int>>> st;
    st.push(make_pair(0,make_pair(0,0)));
    vis[0][0][0] = 0;
    bool fn = false;
    while(true){
        if(now==k) break;
        ans[ni][nj] ^= 1;
        int nni = ni + dx;
        if(nni<0||nni>=h){
            nni = ni;
            dx *= -1;
        }
        int nnj = nj + dy;
        if(nnj<0||nnj>=w){
            nnj = nj;
            dy *= -1;
        }
        ni = nni;
        nj = nnj;
        now++;
        int mask = 0;
        if(dx==-1) mask += 1;
        if(dy==-1) mask += 2;
        if(vis[mask][nni][nnj]==-1){
            vis[mask][nni][nnj] = now;
            st.push(make_pair(mask,make_pair(nni,nnj)));
            continue;
        }
        if(fn) continue;
        stack<pair<int,int>> nxt;
        ll cnt = 0;
        pair<int,pair<int,int>> want = make_pair(mask,make_pair(nni,nnj));
        while(true){
            if(st.top()==want){
                cnt++;
                nxt.push(make_pair(nni,nnj));
                break;
            }
            int nx = st.top().second.first;
            int ny = st.top().second.second;
            cnt++;
            nxt.push(make_pair(nx,ny));
            st.pop();
            continue;
        }
        fn = true;
        ll res = k - now;
        ll can = res / cnt;
        if(can%2==1){
            while(nxt.size()){
                int ni = nxt.top().first;
                int nj = nxt.top().second;
                ans[ni][nj] ^= 1;
                nxt.pop();
            }
        }
        now += can * cnt;
    }
    for(int i = 0;i<h;i++){
        for(int j = 0;j<w;j++){
            if(ans[i][j]==0) cout<<".";
            else cout<<"#";
        }
        cout<<endl;
    }
}