#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair <int, int> pii;
typedef vector <pii> vp;

const int MAX_N = 1000 + 5;

int N, M, a, b;
vp edge[MAX_N];
char col[MAX_N];
ll ans;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
    
    cin >> N >> M >> a >> b;
    for (int i = 1; i <= M; i ++) {
        int x, y, w;
        cin >> x >> y >> w;
        edge[x].emplace_back(y, w);
        edge[y].emplace_back(x, w);
    }
    col[a] = 1; col[b] = 2;
    for (auto [y, w] : edge[a]) {
        (col[y] || (ans += w));
    }
    for (auto [y, w] : edge[b]) {
        (col[y] || (ans += w));
    }
    while (true) {
        int u = -1, nc = -1;
        ll val = 0;
        for (int i = 1; i <= N; i ++) {
            if (!col[i]) {
                ll suma = 0, sumb = 0, sumc = 0;
                for (auto [y, w] : edge[i]) {
                    switch (col[y]) {
                        case 0 : sumc += w; break;
                        case 1 : suma += w; break;
                        case 2 : sumb += w; break;
                        default : assert(false);
                    }
                }
                ll sum = abs(suma - sumb) - sumc;
                if (val < sum) {
                    val = sum; u = i;
                    nc = suma < sumb ? 1 : 2;
                }
            }
        }
        if (u == -1) break;
        col[u] = nc;
        ans -= val;
    }
    cout << ans << '\n';
    for (int i = 1; i <= N; i ++) {
        char c = 0;
        switch (col[i]) {
            case 0 : c = 'C'; break;
            case 1 : c = 'A'; break;
            case 2 : c = 'B'; break;
            default : assert(false);
        }
        cout << c;
    }
    cout << endl;
    
    return 0;
}