#include <bits/stdc++.h>
#define ff first
#define ss second
#define pb push_back
#define int long long
#define all(v) v.begin(), v.end()
using namespace std;
const int mxn = 1e6 + 5, mod = 1e9 + 7, inf = 1e18;
void solve() {
int n, m;
cin >> n >> m;
vector<pair<int, int>> adj[n + 1];
for (int i = 1; i <= m; i++) {
int u, v, w;
cin >> u >> v >> w;
adj[u].pb({v, w});
adj[v].pb({u, w});
}
int res[n + 1][n + 1];
for (int i = 1; i <= n; i++) {
priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> pq;
pq.push({0, i});
vector<int> vis(n + 1, 0), dis(n + 1, inf);
dis[i] = 0;
while (pq.size()) {
int u = pq.top().ss;
pq.pop();
if (vis[u]) continue;
vis[u] = 1;
for (auto[v, len]: adj[u]) {
if (dis[u] + len < dis[v]) {
dis[v] = dis[u] + len;
pq.push({dis[v], v});
}
}
}
for (int j = 1; j <= n; j++) {
res[i][j] = dis[j];
}
}
/*
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
cout << res[i][j] << ' ';
}
cout << '\n';
}
*/
int ans = inf;
string str;
for (int mask = 0; mask < (1 << n); mask++) {
vector<int> col(n + 1, 0);
bool ok1 = false, ok0 = false;
for (int i = 1; i <= n; i++) {
if (mask & (1 << (i - 1))) {
col[i] = 1;
ok1 = true;
}
else {
col[i] = 0;
ok0 = true;
}
}
if (!ok1 || !ok0) {
continue;
}
int mx = 0;
for (int i = 1; i <= n; i++) {
int m0 = inf, m1 = inf;
for (int j = 1; j <= n; j++) {
if (i == j) continue;
if (col[j] == 1) {
m1 = min(m1, res[i][j]);
}
else {
m0 = min(m0, res[i][j]);
}
}
mx = max(mx, min(m1, m0));
}
if (mx < ans) {
ans = mx;
string cur;
for (int i = 1; i <= n; i++) {
if (col[i] == 1) cur += 'D';
else cur += 'B';
}
str = cur;
}
}
cout << ans << '\n';
cout << str;
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(nullptr);
int t = 1;
// cin >> t;
for (int i = 1; i <= t; i++) {
solve();
}
}
