/* -*- coding: utf-8 -*-
 *
 * 3254.cc:  No.3254 Xor, Max and Sum - yukicoder
 */

#include<cstdio>
#include<algorithm>

using namespace std;

/* constant */

const int BN = 30;

/* typedef */

using ll = long long;

/* global variables */

/* subroutines */

/* main */

int main() {
  int n, m;
  scanf("%d%d", &n, &m);

  if (n == 1) { puts("0"); return 0; }
  if (! (n & 1)) { printf("%lld\n", (ll)m * n); return 0; }

  int a0 = 0, a1 = 0;
  for (int i = BN - 1; i >= 0; i--) {
    int bi = 1 << i;
    if (m & bi) {
      if (a0 <= 0) a0 |= bi;
      else a1 |= bi;
    }
    else {
      if (a1 > 0) a0 |= bi, a1 |= bi;
    }
  }

  ll s = (ll)m * (n - 2) + a0 + a1;
  printf("%lld\n", s);

  return 0;
}