import java.util.*; import java.io.*; public class Main { static FastScanner sc = new FastScanner(System.in); static PrintWriter pw = new PrintWriter(System.out); static StringBuilder sb = new StringBuilder(); public static void main(String[] args) throws Exception { if (args.length == 1 && args[0].equals("debug")) { FileReader filereader; BufferedReader is; String path = new File(".").getAbsoluteFile().getParent(); String input = path + File.separator + "_debug_"; String output = path + File.separator + "_answer_" + File.separator; File[] list = new File(input).listFiles(); for (File file : list) { filereader = new FileReader(file); sc = new FastScanner(filereader); pw.println(file.getName()); pw.println("----------------------------------------"); pw.println("output"); long start = System.currentTimeMillis(); solve(); if (new File(output + file.getName()).exists()) { pw.println("----------------------------------------"); pw.println("expect"); filereader = new FileReader(new File(output + file.getName())); is = new BufferedReader(filereader); String s; while ((s = is.readLine()) != null) { pw.println(s); } } pw.println("----------------------------------------"); pw.println((System.currentTimeMillis() - start) + "ms\n"); } } else { solve(); } pw.flush(); } public static void solve() { int h = sc.nextInt(); int w = sc.nextInt(); int x = sc.nextInt(); char[][] map = new char[h][w]; int hmax = ((h-1)/2) % 2 == 0 ? (h+1)/2 : (h-1)/2; int wmax = ((w-1)/2) % 2 == 0 ? (w+1)/2 : (w-1)/2; int max = Math.max(hmax*(w-1)+(h-1),wmax*(h-1)+(w-1)); if((h-1+w-1) > x || max < x || x % 2 != 0){ pw.println(-1); return; }else{ int rem = x - (h-1+w-1); if(rem % 4 != 0){ pw.println(-1); return; } if(hmax*(w-1)+(h-1) >= wmax*(h-1)+(w-1)){ int j = 0; for(int i = 0; i < h; i++){ if(i == h-1){ for(int k = 0; k < w; k++){ map[i][k] = '.'; } }else if(i % 2 != 0){ for(int k = 0; k < w; k++){ if(k != j){ map[i][k] = '#'; }else{ map[i][k] = '.'; } } }else{ int next = Math.min(rem/2,Math.max(w-1-j,j)); if(j+next < w && (i/2) % 2 == 0){ for(int k = 0; k < w; k++){ map[i][k] = '.'; } j += next; }else{ for(int k = 0; k < w; k++){ map[i][k] = '.'; } j -= next; rem -= next*2; } } } }else{ int i = 0; for(int j = 0; j < w; j++){ if(j == w-1){ for(int k = 0; k < h; k++){ map[k][j] = '.'; } }else if(j % 2 != 0){ for(int k = 0; k < h; k++){ if(k != i){ map[k][j] = '#'; }else{ map[k][j] = '.'; } } }else{ int next = Math.min(rem/2,Math.max(h-1-i,i)); for(int k = 0; k < h; k++){ map[k][j] = '.'; } if(i+next < h && (j/2) % 2 == 0){ i += next; }else{ i -= next; rem -= next*2; } } } } } for(int i = 0; i < h; i++) pw.println(new String(map[i])); } static class GeekInteger { public static void save_sort(int[] array) { shuffle(array); Arrays.sort(array); } public static int[] shuffle(int[] array) { int n = array.length; Random random = new Random(); for (int i = 0, j; i < n; i++) { j = i + random.nextInt(n - i); int randomElement = array[j]; array[j] = array[i]; array[i] = randomElement; } return array; } public static void save_sort(long[] array) { shuffle(array); Arrays.sort(array); } public static long[] shuffle(long[] array) { int n = array.length; Random random = new Random(); for (int i = 0, j; i < n; i++) { j = i + random.nextInt(n - i); long randomElement = array[j]; array[j] = array[i]; array[i] = randomElement; } return array; } } } class FastScanner { private BufferedReader reader = null; private StringTokenizer tokenizer = null; public FastScanner(InputStream in) { reader = new BufferedReader(new InputStreamReader(in)); tokenizer = null; } public FastScanner(FileReader in) { reader = new BufferedReader(in); tokenizer = null; } public String next() { if (tokenizer == null || !tokenizer.hasMoreTokens()) { try { tokenizer = new StringTokenizer(reader.readLine()); } catch (IOException e) { throw new RuntimeException(e); } } return tokenizer.nextToken(); } public String nextLine() { if (tokenizer == null || !tokenizer.hasMoreTokens()) { try { return reader.readLine(); } catch (IOException e) { throw new RuntimeException(e); } } return tokenizer.nextToken("\n"); } public long nextLong() { return Long.parseLong(next()); } public int nextInt() { return Integer.parseInt(next()); } public double nextDouble() { return Double.parseDouble(next()); } public String[] nextArray(int n) { String[] a = new String[n]; for (int i = 0; i < n; i++) a[i] = next(); return a; } public int[] nextIntArray(int n) { int[] a = new int[n]; for (int i = 0; i < n; i++) a[i] = nextInt(); return a; } public long[] nextLongArray(int n) { long[] a = new long[n]; for (int i = 0; i < n; i++) a[i] = nextLong(); return a; } }