#include <bits/stdc++.h>

using namespace std;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
using ll = long long;
#define int ll
using ld = long double;
using pii = pair<int, int>;

#define S second
#define F first
#define mp make_pair
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")

#define mispertion ios_base::sync_with_stdio(0),cin.tie(0)
#define sz(x) (int)x.size()
#define all(x) x.begin(),x.end()

const ld PI = 3.1415926535;
const ld eps = 1e-9;
const int N = 1e5 + 2;
const int M = 1.5e6 + 13;
ll mod = 998244353;
const int infi = 2e9;
const ll infl = 1e16;
const int P = 31;

int mult(int a, int b) {
    return a * 1LL * b % mod; }

int sum(int a, int b) {
    if(a + b >= mod)
        return a + b - mod;
    if(a + b < 0)
        return a + b + mod;
    return a + b;
}

ll binpow(ll a, ll n) {
    if (n == 0) return 1;
    if (n % 2 == 1) {
        return binpow(a, n - 1) * a % (mod);
    } else {
        ll b = binpow(a, n / 2);
        return b * b % (mod);
    }
}

struct dsu{
    int p[N], sz[N], cnt;

    void init(int n){
        for(int i = 1; i <= n; i++)
            p[i] = i;
        for(int i = 1; i <= n; i++)
            sz[i] = 1;
        cnt = n;
    }

    int getp(int v){
        if(p[v] == v)
            return v;
        return p[v] = getp(p[v]);
    }

    void uni(int a, int b){
        a = getp(a);
        b = getp(b);
        if(a == b)
            return;
        if(sz[a] > sz[b])
            swap(a, b);
        if(sz[a] == 1)
            cnt--;
        if(sz[b] == 1)
            cnt--;
        p[a] = b;
        sz[b] += sz[a];
    }
};

int n, m, c[N], used[N];
vector<int> g[N];

void dfs(int v, int col){
    used[v] = 1;
    c[v] = col;
    for(auto u : g[v])
        if(!used[u])
            dfs(u, col ^ 1);
}

inline void solve() { 
    cin >> n >> m;
    vector<pair<int, pii>> vec = {};
    for(int i = 0; i < m; i++){
        int u, v, w;
        cin >> u >> v >> w;
        vec.push_back({w, {u, v}});
    }
    int ans;
    sort(all(vec));
    dsu ds;
    ds.init(n);
    for(auto e : vec){
        int u = e.S.F, v = e.S.S;
        int w = e.F;
        if(ds.getp(u) == ds.getp(v))
            continue;
        g[v].push_back(u);
        g[u].push_back(v);
        ds.uni(u, v);
        if(ds.cnt == 0){
            ans = w;
            break;
        }
    }
    cout << ans << '\n';
    for(int i = 1; i <= n; i++){
        if(!used[i])
            dfs(i, 0);
        cout << (c[i] ? 'B' : 'D');
    }
    cout << '\n';
}

signed main() {
    mispertion;
    int t = 1;
    //cin >> t;
    for(int i = 1; i <= t; i ++){
        solve();
    }
    return 0;
}