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#include <bits/stdc++.h>
using namespace std;

const long long maxinf = 10000000000000000;

long long wr[100005][2];
int n, k;

long long dp[100005][2];

bool check(long long mxk)
{
    dp[0][0] = 0;
    for (int i = 1; i <= k; i++)
    {
        dp[i][0] = maxinf;
    }
    for (int i = 1; i <= n; i++)
    {
        for (int j = 0; j <= k; j++)
        {
            if (j == 0)
                dp[j][i & 1] = dp[j][(i ^ 1) & 1] + wr[i][1];
            else
                dp[j][i & 1] = min(dp[j - 1][(i ^ 1) & 1] + wr[i][0], dp[j][(i ^ 1) & 1] + wr[i][1]);

            dp[j][i & 1] = max(dp[j][i & 1], (long long)0);
            if (dp[j][i & 1] > mxk)
                dp[j][i & 1] = maxinf;
            // cout << i << ' ' << j << ' ' << dp[j][i & 1] << '\n';
        }
    }
    if (dp[k][n & 1] > mxk)
        return false;
    return true;
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin >> n >> k;
    // DPS dp[n + 2][k + 2];
    long long s = 0;
    for (int i = 0; i < 2; i++)
    {
        for (int j = 1; j <= n; j++)
        {
            cin >> wr[j][i];
            s += max((long long)0, wr[j][i]);
        }
    }
    long long dd = 0, gg = s, ss;
    // cout << check(4) << '\n';
    // cout << "=====================\n";
    // cout << check(3) << '\n';
    // return 0;
    while (dd < gg)
    {
        ss = (dd + gg) / 2;
        // cout << ss << ' ' << check(ss) << '\n';
        if (check(ss))
        {
            gg = ss;
        }
        else
            dd = ss + 1;
    }
    cout << dd << '\n';
    pair<long long, long long> dp2[n + 2][k + 2]{};
    for (int i = 1; i <= n; i++)
    {
        for (int j = 0; j <= k; j++)
        {
            if (j == 0)
                dp2[i][j] = {dp2[i - 1][j].first + wr[i][1], 0};
            else
            {
                if (dp2[i - 1][j - 1].first + wr[i][0] <= dp2[i - 1][j].first + wr[i][1])
                {
                    dp2[i][j] = {dp2[i - 1][j - 1].first + wr[i][0], i};
                }
                else
                {
                    dp2[i][j] = {dp2[i - 1][j].first + wr[i][1], dp2[i - 1][j].second};
                }
            }
            // dp[j][i & 1] = min(dp[j - 1][(i ^ 1) & 1] + wr[i][0], dp[j][(i ^ 1) & 1] + wr[i][1]);

            dp2[i][j].first = max(dp2[i][j].first, (long long)0);
            if (dp2[i][j].first > ss)
            {
                dp2[i][j].first = maxinf;
            }
            // cout << i << ' ' << j << ' ' << dp[j][i & 1] << '\n';
        }
    }
    int lop = n, lob2 = k;
    bool wh[n + 2]{};
    while (lop>=0)
    {
        // cout<<dp2[lop][lob2].second<<'\n'<<flush;
        wh[dp2[lop][lob2].second] = 1;
        lop = dp2[lop][lob2].second - 1;
        lob2--;
    }
    for(int i=1;i<=n;i++){
        cout<<(wh[i]?'A':'B');
    }
}