#include <bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
//using namespace __gnu_pbds;

// #pragma GCC optimize("unroll-loops")
// #pragma GCC optimize("O3")

#define speed ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define russian setlocale(LC_ALL,"Russian_Russia.20866");
#define file freopen("onlyone.in", "r", stdin), freopen("onlyone.out", "w", stdout);
#define ll long long
#define big __int128
#define ull unsigned long long
#define ld long double
#define pll pair<ll, ll>
#define pli pair<ll, int>
#define pii pair<int, int>
#define all(s) s.begin(), s.end()
#define pb push_back
#define ins insert
#define sz(x) x.size()
#define F first
#define S second
#define lb lower_bound
#define ub upper_bound
#define mem(x) memset(x, 0, sizeof(x))
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

const int N = 500010;
const int B = 448;
const ll mod = 998244353;
const ll P = 263;
const ld pi = acos(-1);
const ll inf = (ll)1e18;
const ll ntr = (ll)-1e18;

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

ll sub(ll a, ll b) {
    return (a - b + mod) % mod;
}

ll mul(ll a, ll b) {
    return a * 1LL * b % mod;
}

ll binpow(ll a, ll n) {
    ll res = 1;
    while(n) {
        if (n & 1) res = mul(res, a);
        a = mul(a, a);
        n >>= 1;
    }
    return res;
}

ll inv(ll x) {
    return binpow(x, mod - 2);
}
int n, m;
ll dst[20][20];
void sub1() {
    pair<ll, string> ans = {LLONG_MAX, ""}, cur = {0LL, ""};
    vector<int> b, d;
    for(int msk = 1; msk < (1 << n) - 1; msk++) {
        b.clear(); d.clear();
        cur = {0LL, ""};
        for(int i = 0; i < n; i++) {
            if((msk & (1 << i))) {
                cur.S += 'B';
                b.pb(i + 1);
            }
            else {
                cur.S += 'D';
                d.pb(i + 1);
            }
        }
        for(auto i: b) {
            for(auto j: d) {
                cur.F = max(cur.F, dst[i][j]);
            }
        }
        for(auto i: d) {
            for(auto j: b) {
                cur.F = max(cur.F, dst[i][j]);
            }
        }
        if(ans.F > cur.F) ans = cur;
    }
    cout << ans.F << '\n' << ans.S << '\n';
}
void solve() {
    cin >> n >> m;
    for(int i = 1; i <= n; i++) {
        for(int j = 1; j <= n; j++) {
            dst[i][j] = 1e17;
        }
    }
    for(int i = 1; i <= n; i++) {
        dst[i][i] = 0LL;
    }
    for(int i = 1, v1, v2, w; i <= m; i++) {
        cin >> v1 >> v2 >> w;
        dst[v1][v2] = min(dst[v1][v2], 1LL * w);
        dst[v2][v1] = min(dst[v2][v1], 1LL * w);
    }
    for(int k = 1; k <= n; k++) {
        for(int i = 1; i <= n; i++) {
            for(int j = 1; j <= n; j++) {
                dst[i][j] = min(dst[i][j], dst[i][k] + dst[k][j]);
            }
        }
    }
    if(n <= 16) {
        sub1();
        return;
    }
}
signed main() {
    speed;
    //file
    int test = 1;
    //cin >> test;
    while(test--) {
        solve();
    }
}