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#include <bits/stdc++.h>
using namespace std;
using LL = long long;
#define FOR(i, l, r) for(int i = (l); i <= (r); ++i)
#define REP(i, n) FOR(i, 0, (n) - 1)
#define ssize(x) int(x.size())
template<class A, class B> auto& operator<<(ostream &o, pair<A, B> p) {
    return o << '(' << p.first << ", " << p.second << ')';
}
template<class T> auto operator<<(ostream &o, T x) -> decltype(x.end(), o) {
    o << '{'; int i = 0; for(auto e : x) o << (", ")+2*!i++ << e; return o << '}';
}
#ifdef DEBUG
#define debug(x...) cerr << "[" #x "]: ", [](auto... $) {((cerr << $ << "; "), ...); }(x), cerr << '\n'
#else
#define debug(...) {}
#endif

int main() {
    cin.tie(0)->sync_with_stdio(0);

    int n, k;
    cin >> n >> k;

    vector<int> a(n), b(n);
    REP(i, n) cin >> a[i];
    REP(i, n) cin >> b[i];

    auto check = [&](LL bound, bool print = false) {
        LL inf = 1e18;
        vector dp(n + 1, vector<LL>(n + 1, inf));
        dp[0][0] = 0;
        REP(i, n) REP(j, n) {
            if(dp[i][j] <= bound) {
                dp[i + 1][j + 1] = min(dp[i + 1][j + 1], max(dp[i][j] + a[i], 0LL));
                dp[i + 1][j] = min(dp[i + 1][j], max(dp[i][j] + b[i], 0LL));
            }
        }

        if(print) {
            int j = k;
            string out;
            for(int i = n - 1; i >= 0; i--) {
                if(dp[i + 1][j] == max(dp[i][j] + b[i], 0LL)) 
                    out.push_back('B');
                else {
                    out.push_back('A');
                    j--;
                }
            }
            reverse(out.begin(), out.end());
            cout << out.data() << "\n";
        }
        return dp[n][k] <= bound;
    };

    LL l = 0, r = n * 1e9;
    while(l < r) {
        LL m = (l + r) / 2;
        if(check(m)) 
            r = m;
        else
            l = m + 1;
    }

    cout << l << "\n";
    check(l, true);
}