#include<bits/stdc++.h>

using namespace std;

#define gc c=getchar()
#define r(x) read(x)
#define ll long long

template<typename T>
inline void read(T &x){
    x=0;T k=1;char gc;
    while(!isdigit(c)){if(c=='-')k=-1;gc;}
    while(isdigit(c)){x=x*10+c-'0';gc;}x*=k;
}

inline bool check(int x, int n, int m, vector<int> &a){
    vector<vector<int>> dp(n + 1, vector<int>(m + 1, 0));
    vector<int> sufmax(vector<int>(n + 1, 0));
    for(int j = m - 1; ~j; --j){
        int res = a[j];
        for(int i = 0; i < n; ++i){
            if(res && sufmax[i + 1] + 1 <= x){
                dp[i][j] = sufmax[i + 1] + 1;
                --res;
            }
            else{
                dp[i][j] = sufmax[i];
            }
        }
        if(res) return false;
        for(int i = n - 1; ~i; --i){
            sufmax[i] = max(sufmax[i], max(sufmax[i + 1], dp[i][j]));
        }
    }
    return true;
}

inline void output(int x, int n, int m, vector<int> &a){
    vector<vector<int>> dp(n + 1, vector<int>(m + 1, 0));
    vector<vector<char>> ans(n, vector<char>(m));
    vector<int> sufmax(vector<int>(n + 1, 0));
    for(int j = m - 1; ~j; --j){
        int res = a[j];
        for(int i = 0; i < n; ++i){
            if(res && sufmax[i + 1] + 1 <= x){
                dp[i][j] = sufmax[i + 1] + 1;
                --res;
                ans[i][j] = '#';
            }
            else{
                dp[i][j] = sufmax[i];
                ans[i][j] = '.';
            }
        }
        if(res) assert(0);
        for(int i = n - 1; ~i; --i){
            sufmax[i] = max(sufmax[i], max(sufmax[i + 1], dp[i][j]));
        }
    }
    printf("%d\n", x);
    for(int i = 0; i < n; ++i){
        for(int j = 0; j < m; ++j){
            putchar(ans[i][j]);
        }
        putchar('\n');
    }
}

void solve(){
    int n, m; r(n), r(m);
    vector<int> a;
    for(int i = 0; i < m; ++i){
        int x; r(x);
        a.push_back(x);
    }
    int l = 0, r = min(n, m), ans;
    while(l <= r){
        int mid = (l + r) >> 1;
        if(check(mid, n, m, a)){
            ans = mid;
            r = mid - 1;
        }
        else{
            l = mid + 1;
        }
    }
    output(ans, n, m, a);
}

int main(){
    // freopen(".in","r",stdin);
    // freopen(".out","w",stdout);
    int T; r(T);
    while(T--){
        solve();
    }
    return 0;
}