#include<bits/stdc++.h>
#define rep(i,j,k) for(int i=j;i<=k;i++)
#define repp(i,j,k) for(int i=j;i>=k;i--)
#define ls(x) (x<<1)
#define rs(x) ((x<<1)|1)
#define mp make_pair
#define sec second
#define fir first
#define pii pair<int,int>
#define lowbit(i) i&-i
#define int long long
#define double long double
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
const int N=2e5+5,M=6,S=(1<<15)+5,inf=(ll)8e18+7,mo=998244353;
const double eps=1e-8;
void read(int &p){
	int x=0,w=1;
	char ch=0;
	while(!isdigit(ch)){
		if(ch=='-')w=-1;
		ch=getchar();
	}
	while(isdigit(ch)){
		x=(x<<1)+(x<<3)+ch-'0';
		ch=getchar();
	}
	p=x*w;
}
int T;
int n,m,a[N];
vector<int>res[N];
int edp[N];
bool check(int k){
    rep(i,1,n){
        rep(j,1,m)
            res[i][j]=0;
    }
    rep(i,1,k)
        edp[i]=n-i+1;
    rep(i,1,m){
        rep(j,1,k)
            res[edp[j]][i]=1;
        int cnt=a[i]-k;
        if(cnt<=0)continue;
        rep(j,1,k){
            int npos=edp[j]-1;
            while(cnt&&npos&&!res[npos][i])
                cnt--,res[npos][i]=1,npos--;
            edp[j]=npos+1;
        }
        if(cnt)return 0;
    }
    rep(j,1,m){
        int cntb=0;
        rep(i,1,n){
            if(!res[i][j])continue;
            if(cntb==a[j])res[i][j]=0;
            else cntb++;
        }
    }
    return 1;
}
void solve(){
    read(n),read(m);
    rep(i,1,n){
        res[i].clear();
        rep(j,0,m)
            res[i].push_back(0);
    }
    rep(i,1,m)
        read(a[i]);
    int le=1,ri=n,ans=n;
    while(le<=ri){
        int mid=(le+ri)>>1;
        if(check(mid))ans=mid,ri=mid-1;
        else le=mid+1;
    }
    printf("%lld\n",ans);
    check(ans);
    rep(i,1,n){
        rep(j,1,m)
            printf("%c",res[i][j]?'#':'.');
        puts("");
    }
}
signed main(){
    read(T);
    while(T--)
        solve();
    return 0;
}