//#include "game.h"
//#pragma GCC optimize("conserve-stack")
#pragma GCC optimize("Ofast,unroll-loops")
#include<bits/stdc++.h>
#define int long long
#define ll long long
#define down cout<<'\n';
#define debug cout<<" cucuucucuuu",down
#define NHP     ios_base::sync_with_stdio(0);cout.tie(0);cin.tie(0);
#define modwwe  int t;cin>>t; while(t--)
#define bit(i,j) (i>>j&1)
#define sobit(a) __builtin_popcountll(a)
#define task "test"
#define fin(x) freopen(x".inp","r",stdin)
#define fou(x) freopen(x".ans","w",stdout)
#define pb push_back
#define checktime   cerr << (double)clock() / CLOCKS_PER_SEC * 1000  << " ms";
using namespace std;
#define getchar_unlocked getchar

inline int scan()
{
    char c = getchar_unlocked();
    int x = 0;
    while(c<'0'||c>'9')
    {
        c=getchar_unlocked();
    }
    while(c>='0'&&c<='9')
    {
        x=(x<<1)+(x<<3)+c-'0';
        c=getchar_unlocked();
    }
    return x;
}

void phongbeo();
const int inf=1e9;
const int mod2=1e9+9;
const int  mod1=998244353;
struct icd
{
    long double a;
    int b;
};
struct ib
{
    int a;
    int b;
};
struct ic
{
    int a,b,c;
};
struct id
{
    int a,b,c,d;
};
struct ie
{
    int a,b,c,d,e;

};

int n,m,s1,s2,s4,s3,sf,k,s5,s6,mx,s7,s8,s9,mx2,res,dem2=0,dem=0,s33,dem3,dem4,l,r,mid,l2,r2,center;
int  i,s10,s12;
int kk;
int el=19;

main()
{
#ifndef ONLINE_JUDGE
    //fin(task);
    //fou(task);
#endif
    NHP
    /// cin>>s1;
///modwwe
    phongbeo(),down
    // checktime
}
vector<ic> v;
bool dp[500001];
struct dsu
{
    ib dsu[500001];
    int get(int x)
    {
        if(dsu[x].b!=x) dsu[x].b=get(dsu[x].b);
        return dsu[x].b;
    }
    void noi(int x,int y)
    {
        if(dsu[x].a<dsu[y].a) swap(x,y);
        dsu[x].a+=dsu[y].a;
        dsu[y].b=x;
    }
    void reset()
    {
        for(int i=1; i<=n; i++)
            dsu[i]= {1,i};
    }
} ds;
vector<int> v2[500001];
bool cmp(ic a,ic b)
{
    return a.c<b.c;
}
 void dfs(int x,int y)
  {
       dp[x]=1-dp[y];
       for(auto f:v2[x])
        if(f!=y)
        dfs(f,x);
  }
void phongbeo()
{
    cin>>n>>m;
    for(int i=1; i<=m; i++)
    {
        cin>>l>>r>>s2;
        v.pb({l,r,s2});
    }
    ds.reset();
    sort(v.begin(),v.end(),cmp);
    for(auto x:v)
    {
        s2=ds.get(x.a);
        s3=ds.get(x.b);
        if(s2!=s3)
        {v2[x.a].pb({x.b});
        v2[x.b].pb(x.a);
            ds.noi(s2,s3);
            s5=x.c;
        }
    }
    dfs(1,0);
    cout<<s5,down
     for(int i=1;i<=n;i++)
        if(dp[i])cout<<"D";
     else cout<<"B";
}