#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9;
void solve() {
  int n, m;
  cin >> m >> n;
  vector<int> a(n);
  for (int i = 0; i < n; i++)
    cin >> a[i];

  vector<vector<int>> pre(n + 1, vector<int>(m));
  for (int i = 0; i < n; i++) {
    int mx = 0;
    for (int j = 0; j < m; j++) {
      if (j >= m - a[i]) {
        pre[i + 1][j] = mx + 1;
      }
      pre[i + 1][j] = max(pre[i + 1][j], pre[i][j]);
      mx = max(mx, pre[i][j]);
    }
  }
  vector<vector<int>> suf(n + 1, vector<int>(m));
  for (int i = n - 1; i >= 0; i--) {
    int mx = 0;
    for (int j = m - 1; j >= 0; j--) {
      if (j < a[i]) {
        suf[i][j] = mx + 1;
      }
      suf[i][j] = max(suf[i][j], suf[i + 1][j]);
      mx = max(mx, suf[i + 1][j]);
    }
  }

  int ans = INF;
  for (int i = 1; i < n; i++) {
    vector<int> suf_mx(m + 1);
    for (int j = m - 1; j >= 0; j--)
      suf_mx[j] = max(suf_mx[j + 1], suf[i][j]);
    int cut = suf_mx[0];
    for (int j = 0; j < m; j++) {
      cut = max(cut, pre[i][j] + suf_mx[j + 1]);
    }
    ans = min(ans, cut);
  }
  int cut0 = 0, cutn = 0;
  for (int j = 0; j < m; j++) {
    cut0 = max(cut0, pre[n][j]);
    cutn = max(cutn, suf[0][j]);
  }
  ans = min(ans, cut0);
  ans = min(ans, cutn);

  cout << ans << "\n";
  for (int i = 1; i < n; i++) {
    vector<int> suf_mx(m + 1);
    for (int j = m - 1; j >= 0; j--)
      suf_mx[j] = max(suf_mx[j + 1], suf[i][j]);
    int cut = suf_mx[0];
    for (int j = 0; j < m; j++) {
      cut = max(cut, pre[i][j] + suf_mx[j + 1]);
    }
    // for (int j = 0; j < m; j++) {
    //   if (cut == pre[i][j] + suf_mx[j + 1]) {
    //     cout << "!!!" << i << " " << j << " " << endl;
    //   }
    // }
    if (cut == ans) {
      // cout << "!!!" << i << " " << cut << endl;
      for (int k = 0; k < m; k++) {
        for (int l = 0; l < i; l++) {
          cout << ".#"[k >= m - a[l]];
        }
        for (int l = i; l < n; l++) {
          cout << ".#"[k < a[l]];
        }
        cout << "\n";
      }
      return;
    }
  }

  if (ans == cut0) {
    for (int i = 0; i < m; i++) {
      for (int j = 0; j < n; j++) {
        cout << ".#"[i >= m - a[j]];
      }
      cout << "\n";
    }
    return;
  }
  if (ans == cutn) {
    for (int i = 0; i < m; i++) {
      for (int j = 0; j < n; j++) {
        cout << ".#"[i < a[j]];
      }
      cout << "\n";
    }
    return;
  }

  assert(0);
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);

  int t;
  cin >> t;
  while (t--) {
    solve();
  }
}

/*

1
5 5
4 5 1 3 5

*/