Students in a class are making towers of blocks. Each student makes a (non-zero) tower by stacking pieces lengthwise on top of each other. n of the students use pieces made of two blocks and m of the students use pieces made of three blocks.

The students don’t want to use too many blocks, but they also want to be unique, so no two students’ towers may contain the same number of blocks. Find the minimum height necessary for the tallest of the students' towers.

Input

The first line of the input contains two space-separated integers n and m (0 ≤ n, m ≤ 1 000 000, n + m > 0) — the number of students using two-block pieces and the number of students using three-block pieces, respectively.

Output

Print a single integer, denoting the minimum possible height of the tallest tower.

Examples

Input

1 3


Output

9


Input

3 2


Output

8


Input

5 0


Output

10

Note

In the first case, the student using two-block pieces can make a tower of height 4, and the students using three-block pieces can make towers of height 3, 6, and 9 blocks. The tallest tower has a height of 9 blocks.

In the second case, the students can make towers of heights 2, 4, and 8 with two-block pieces and towers of heights 3 and 6 with three-block pieces, for a maximum height of 8 blocks.
#include <bits/stdc++.h>
using namespace std;
mt19937_64 rang(
    chrono::high_resolution_clock::now().time_since_epoch().count());
long long mpow(long long base, long long exp);
long long power(long long a, long long b);
const long long mod = 1e9 + 7;
struct node {
  set<int> s;
};
struct segTree {
  long long arr[2001];
  long long res[8003];
  int operation_arr[4003];
  int NO_OPERATION = 0;
  void init(int x, int lo, int hi) {
    if (lo == hi) {
      res[x] = arr[lo];
      return;
    }
    int mid = (lo + hi) / 2;
    init(2 * x, lo, mid);
    init(2 * x + 1, mid + 1, hi);
    update_point(x);
  }
  int merge_operation(int a, int b) { return (a ^ b); }
  long long merge_results(int a, int b) { return a + b; }
  void modify(int x, int lo, int hi, int l, int r, int op) {
    prop(x, lo, hi);
    if (lo >= l && hi <= r) {
      operation_arr[x] = merge_operation(operation_arr[x], op);
      return;
    }
    int mid = (lo + hi) / 2;
    if (lo > r || hi < l) return;
    modify(2 * x, lo, mid, l, r, op);
    modify(2 * x + 1, mid + 1, hi, l, r, op);
    update(x, lo, hi);
  }
  int get_sum(int x, int lo, int hi, int l, int r) {
    if (lo >= l && hi <= r) return res[x];
    if (lo > r || hi < l) return 0;
    int mid = (lo + hi) / 2;
    return get_sum(2 * x, lo, mid, l, r) +
           get_sum(2 * x + 1, mid + 1, hi, l, r);
  }
  void point_modify(int x, int lo, int hi, int pos, long long val) {
    if (lo == hi) {
      res[x] = val;
      return;
    }
    int mid = (lo + hi) / 2;
    if (pos <= mid)
      point_modify(2 * x, lo, mid, pos, val);
    else
      point_modify(2 * x + 1, mid + 1, hi, pos, val);
    update_point(x);
  }
  long long max_query(int x, int lo, int hi, int l, int r) {
    if (lo >= l && hi <= r) return res[x];
    if (lo > r || hi < l) return -1;
    int mid = (lo + hi) / 2;
    return max(max_query(2 * x, lo, mid, l, r),
               max_query(2 * x + 1, mid + 1, hi, l, r));
  }
  void update_point(int x) { res[x] = max(res[2 * x], res[2 * x + 1]); }
  int query(int x, int lo, int hi, int l, int r) {
    prop(x, lo, hi);
    if (lo >= l && hi <= r) return operate(res[x], operation_arr[x], lo, hi);
    if (lo > r || hi < l) return 0;
    int mid = (lo + hi) / 2;
    return merge_results(query(2 * x, lo, mid, l, r),
                         query(2 * x + 1, mid + 1, hi, l, r));
  }
  int kth_one(int x, int lo, int hi, int k) {
    if (lo == hi) return lo;
    int v1 = res[2 * x];
    int mid = (lo + hi) / 2;
    if (k <= v1)
      return kth_one(2 * x, lo, mid, k);
    else
      return kth_one(2 * x + 1, mid + 1, hi, k - v1);
  }
  void prop(int x, int lo, int hi) {
    if (lo == hi) return;
    int mid = (hi + lo) / 2;
    long long len = mid - lo + 1;
    operation_arr[2 * x] =
        merge_operation(operation_arr[2 * x], operation_arr[x]);
    operation_arr[2 * x + 1] =
        merge_operation(operation_arr[2 * x + 1], operation_arr[x]);
    operation_arr[x] = NO_OPERATION;
    update(x, lo, hi);
  }
  int operate(int val, int operatr, int l, int r) {
    if (operatr == NO_OPERATION) return val;
    int sz = r - l + 1;
    return sz - val;
  }
  void update(int x, int lo, int hi) {
    if (lo == hi) return;
    int mid = (lo + hi) / 2;
    long long len1 = (mid - lo + 1);
    long long len2 = (hi - mid);
    res[x] = merge_results(
        operate(res[2 * x], operation_arr[2 * x], lo, mid),
        operate(res[2 * x + 1], operation_arr[2 * x + 1], mid + 1, hi));
  }
};
struct FenwickTree {
  int arr[100];
  int n;
  void update(int i, int delta) {
    while (i <= n) {
      arr[i] += delta;
      i = i + (i & (-i));
    }
  }
  int sum(int i) {
    if (i == 0) return 0;
    int res = 0;
    while (i > 0) {
      res = res + arr[i];
      i -= (i & (-i));
    }
    return res;
  }
};
struct dsu {
  int par[1001];
  int size_set[1001];
  int get_par(int u) {
    vector<int> temp;
    while (par[u] != u) {
      temp.push_back(u);
      u = par[u];
    }
    for (int i : temp) par[i] = u;
    return u;
  }
  void union_set(int a, int b) {
    a = get_par(a);
    b = get_par(b);
    if (a == b) return;
    if (size_set[a] < size_set[b]) {
      int temp = a;
      a = b;
      b = temp;
    }
    par[b] = a;
    size_set[a] += size_set[b];
  }
};
int check(string s1, string s2) {
  int n1 = s1.size();
  int n2 = s2.size();
  s1 = '$' + s1;
  s2 = '$' + s2;
  int dp[n1 + 1][n2 + 1];
  for (int j = 0; j <= n2; j++) dp[0][j] = 0;
  dp[0][0] = 1;
  for (int i = 1; i <= n1; i++) {
    dp[i][0] = 0;
  }
  int i1 = 1;
  while (i1 <= n1 && s1[i1] == '*') {
    dp[i1][0] = 1;
    i1++;
  }
  int sum[n2 + 1];
  int s = 0;
  for (int i = 0; i <= n2; i++) s = s + dp[0][i], sum[i] = s;
  for (int i = 1; i <= n1; i++) {
    for (int j = 1; j <= n2; j++) {
      char c1 = s1[i];
      char c2 = s2[j];
      if (c1 == '*') {
        if (sum[j] > 0)
          dp[i][j] = 1;
        else
          dp[i][j] = 0;
      } else if (c1 == '?') {
        dp[i][j] = dp[i - 1][j - 1];
      } else {
        if (c1 != c2)
          dp[i][j] = 0;
        else
          dp[i][j] = dp[i - 1][j - 1];
      }
    }
    s = 0;
    for (int j = 0; j <= n2; j++) {
      s += dp[i][j];
      sum[j] = s;
    }
  }
  return dp[n1][n2];
}
int gcd(int a, int b) {
  if (a == 0) return b;
  if (b == 0) return a;
  return gcd(b, a % b);
}
long long pw1[21];
long long pw2[21];
long long m1 = 1e9 + 7;
long long m2 = 1e9 + 9;
long long base = 30;
pair<long long, long long> string_hash(string s) {
  long long res1 = 0, res2 = 0;
  for (int i = 0; i < s.size(); i++) {
    int v = s[i] - 'a';
    res1 = (res1 + v * pw1[i]) % m1;
    res2 = (res2 + v * pw2[i]) % m2;
  }
  return make_pair(res1, res2);
}
bool isOverflow(long long a, long long b) {
  if (a == 0 || b == 0) return false;
  if (a <= LLONG_MAX / b)
    return false;
  else
    return true;
}
bool isOverflow_add(long long a, long long b) {
  long long res = a + b;
  if (res - a == b && res - b == a) return 0;
  return 1;
}
int b[301];
string get_next(string s1, int sod) {
  int pos = -1;
  int digit = -1;
  int n = s1.size();
  int sum = sod;
  int sum_left = -1;
  for (int i = 0; i < s1.size(); i++) {
    int left = n - i - 1;
    int d = s1[i] - '0';
    for (int j = d + 1; j <= 9; j++) {
      if (sum - j <= 9 * left && sum - j >= 0) {
        pos = i, digit = j;
        sum_left = sum - j;
        break;
      }
    }
    sum -= d;
  }
  if (pos != -1) {
    s1[pos] = digit + '0';
    for (int i = pos + 1; i < s1.size(); i++) {
      int left = n - i - 1;
      int dig = -1;
      for (int j = 0; j <= 9; j++) {
        if (sum_left - j <= 9 * left && sum_left - j >= 0) {
          dig = j;
          break;
        }
      }
      s1[i] = '0' + dig;
      sum_left -= dig;
    }
    return s1;
  } else {
    int len = -1;
    int sod_left = -1;
    int first_digit = -1;
    int l = s1.size() + 1;
    int b = 1;
    while (b) {
      for (int j = 1; j <= 9; j++) {
        if (sod - j >= 0 && sod - j <= 9 * (l - 1)) {
          len = l;
          sod_left = sod - j;
          first_digit = j;
          b = 0;
          break;
        }
      }
      l++;
    }
    string res = "";
    res = res + to_string(first_digit);
    for (int i = 1; i <= len - 1; i++) {
      int left = len - i - 1;
      int dig = -1;
      for (int j = 0; j <= 9; j++) {
        if (sod_left - j >= 0 && sod_left - j <= 9 * left) {
          dig = j;
          break;
        }
      }
      sod_left -= dig;
      res = res + to_string(dig);
    }
    return res;
  }
  return "";
}
long long n;
long long get_div(long long k) { return n / k; }
vector<long long> temp = {2, 3, 5, 7};
long long cnt = 0;
void get_taken(int i, long long val, int j) {
  if (i == 4) {
    if (j == 0) cnt += get_div(val);
    return;
  }
  if (j > 0) get_taken(i + 1, val * temp[i], j - 1);
  get_taken(i + 1, val, j);
}
void solve() {
  long long n, m;
  cin >> n >> m;
  long long i = 1;
  while (1) {
    int div = i / 2 + i / 3 - i / 6;
    if (div >= m + n && (i / 3) >= m && (i / 2) >= n) {
      cout << i << "\n";
      return;
    }
    i++;
  }
}
int main() {
  ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  srand(chrono::high_resolution_clock::now().time_since_epoch().count());
  int t = 1;
  while (t--) {
    solve();
  }
  return 0;
}
long long mpow(long long base, long long exp) {
  base %= mod;
  long long result = 1;
  while (exp > 0) {
    if (exp & 1) result = ((long long)result * base) % mod;
    base = ((long long)base * base) % mod;
    exp >>= 1;
  }
  return result;
}
long long power(long long a, long long b) {
  long long res = 1;
  while (b > 0) {
    if (b % 2 == 0) {
      b /= 2;
      if (isOverflow(a, a)) return LLONG_MAX;
      a = a * a;
    } else {
      if (isOverflow(res, a)) return LLONG_MAX;
      res = res * a;
      b--;
    }
  }
  return res;
}
