#include <bits/stdc++.h>
#define ll              long long
#define pii             pair<int,int>
#define pll             pair<ll,ll>
#define rep(i,m,n)      for(int i=(m); i<=(n); i++)
#define reb(i,m,n)      for(int i=(m); i>=(n); i--)
#define iter(id, v)     for(auto id : v)
#define fs              first
#define se              second
#define MP              make_pair
#define pb              push_back
#define bit(msk, i)     ((msk >> i) & 1)
#define SZ(v)           (ll)v.size()
#define ALL(v)          v.begin(),v.end()

using namespace std;

mt19937_64 rd(chrono :: steady_clock :: now ().time_since_epoch().count());
ll Rand (ll l, ll r) { return uniform_int_distribution<ll> (l, r) (rd); }

const int N = 2e5 + 7;
const int Mod = 1e9 + 2022; ///loonf mod sai
const ll INF = 1e18;
const ll BASE = 137;
const int szBL = 320;

struct Edge {
    int u, v, w;
};

int n, m;
int a[N];
bool dd[N];
vector<Edge> edges;

vector<int> ke[N];
int vis[N];

void dfs (int u, int typ) {
    vis[u] = typ;
    iter (&v, ke[u]) if (vis[v] == -1) dfs(v, typ ^ 1);
}

void solution() {
    cin >> n >> m;
    rep (i, 1, m) {
        int u, v, w;
        cin >> u >> v >> w;
        edges.pb({u, v, w});
    }
    sort (ALL(edges), [] (Edge A, Edge B) { return A.w < B. w; });
    int rem = n, mxW = 0;
    iter (&id, edges) {
        int u = id.u, v = id.v, w = id.w;
        if (dd[u] == 0) -- rem;
        if (dd[v] == 0) -- rem;
        dd[u] = dd[v] = 1;
        ke[u].pb(v);
        ke[v].pb(u);
        mxW = w;
        if (rem == 0) break;
    }
    cout << mxW <<"\n";
    rep (i, 1, n) vis[i] = -1;
    rep (i, 1, n) if (vis[i] == -1) dfs(i, 1);
    rep (i, 1, n) cout << (vis[i] == 1 ? 'D' : 'B');

}

#define file(name) freopen(name".inp","r",stdin); \
freopen(name".out","w",stdout);
int main () {
//    file("c");
    ios_base :: sync_with_stdio(false); cin.tie(0); cout.tie(0);
    int num_Test = 1;
//    cin >> num_Test;
    while (num_Test--)
        solution();
}
/*
no bug +8
chu y break hay return se lam hong logic
xet transition cua i va i + 1
construct ket qua
chu y truong hop : KHONG CO GI

ko làm được

hướng 1: đổi hướng làm
hướng 2: đưa ra nhận xét

tim mo hinh bai toan sau khi doc de

trung ten bien trong ham gan nhat co the dan den sai

5 6
3 2 3
4 2 1
5 3 9
1 3 5
1 4 2
2 3 1


*/