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#include <bits/stdc++.h>
#define REP(i,n) for (int _n=(n), i=0;i<_n;++i)
#define FOR(i,a,b) for (int i=(a),_b=(b);i<=_b;++i)
#define FORD(i,a,b) for (int i=(a),_b=(b);i>=_b;--i)
#define TRACE(x) std::cerr << "TRACE(" #x ")" << std::endl;
#define DEBUG(x) std::cerr << #x << " = " << (x) << std::endl;
using std::int8_t;
using std::int64_t;

void init_io() {
  std::cin.tie(nullptr);
  std::ios::sync_with_stdio(false);
}

struct Painting {
  int value[2] = {};
};

// read_input
int num_paintings;
std::vector<Painting> paintings;
int target_count_0;

// find_initial_solution
std::vector<int8_t> initial_solution;
int64_t initial_score;
int initial_count_0;

int update_to_whom;
int num_required_updates;

// solve
std::vector<int8_t> solution;

std::vector<int8_t> good_solution;
int64_t good_solution_score;

void read_input() {
  std::cin >> num_paintings >> target_count_0;
  paintings.resize(num_paintings);
  REP(i, 2) {
    for (Painting &p : paintings) {
      std::cin >> p.value[i];
    }
  }
}

void find_initial_solution() {
  initial_solution.reserve(num_paintings);
  initial_score = 0;
  initial_count_0 = 0;
  int64_t sum = 0;

  for (const Painting &p : paintings) {
    const int who = p.value[0] <= p.value[1] ? 0 : 1;
    if (who == 0) ++initial_count_0;
    initial_solution.push_back(who);
    sum += p.value[who];
    sum = std::max<int64_t>(sum, 0);
    initial_score = std::max(initial_score, sum);
  }
}

void find_updates() {
  if (initial_count_0 <= target_count_0) {
    update_to_whom = 0;
    num_required_updates = target_count_0 - initial_count_0;
  } else {
    update_to_whom = 1;
    num_required_updates = initial_count_0 - target_count_0;
  }
}

struct Increment {
  int index = 0;
  int value = 0;
};

inline bool operator<(const Increment &a, const Increment &b) {
  return a.value < b.value;
}

bool try_solve(const int64_t score_limit) {
  solution = initial_solution;

  int num_updates_left = num_required_updates;
  if (num_updates_left == 0) return true;
  int64_t sum = 0;
  std::multiset<Increment> increments;
  int64_t increments_total = 0;
  REP(painting_idx, num_paintings) {
    const Painting &p = paintings[painting_idx];
    const int current = initial_solution[painting_idx];
    const int val = p.value[current];
    sum += val;
    if (current != update_to_whom) {
      Increment increment;
      increment.index = painting_idx;
      increment.value = p.value[update_to_whom] - val;
      increments.insert(increment);
      increments_total += increment.value;
    }
    while (sum < 0) {
      auto it = increments.begin();
      if (it == increments.end()) {
        sum = 0;
      } else {
        Increment increment = *it;
        increments.erase(it);
        sum += increment.value;
        increments_total -= increment.value;
        if (sum > 0) {
          increment.value = sum;
          sum = 0;
          increments.insert(increment);
          increments_total += increment.value;
        } else {
          solution[increment.index] = update_to_whom;
          --num_updates_left;
          if (num_updates_left == 0) return true;
        }
      }
    }
    while (sum + increments_total > score_limit) {
      auto it = increments.end();
      assert (it != increments.begin());
      --it;
      increments_total -= it->value;
      increments.erase(it);
    }
  }
  for (const auto &increment : increments) {
    solution[increment.index] = update_to_whom;
    --num_updates_left;
    if (num_updates_left == 0) return true;
  }
  return false;
}

void solve() {
  int64_t impossible_score = initial_score - 1;

  int64_t possible_score = 0;
  for (const Painting &p : paintings) {
    possible_score += std::max(std::max(p.value[0], p.value[1]), 0);
  }
  // Go 1 too far to make sure a solution actually gets generated.
  possible_score += 1;

  while (possible_score - impossible_score > 1) {
    const int64_t score = impossible_score + (possible_score - impossible_score) / 2;
    if (try_solve(score)) {
      good_solution = solution;
      good_solution_score = score;
      possible_score = score;
    } else {
      impossible_score = score;
    }
  }
}

void print_solution_score() {
  std::cout << good_solution_score << "\n";
}

void print_solution() {
  for (const auto who : good_solution) {
    const char c = 'A' + who;
    std::cout << c;
  }
  std::cout << '\n';
}

int main() {
  init_io();
  read_input();
  find_initial_solution();
  find_updates();
  solve();
  print_solution_score();
  print_solution();
}