// Author: kyEEcccccc

#include <bits/stdc++.h>

using namespace std;

using LL = long long;
using ULL = unsigned long long;

#define F(i, l, r) for (int i = (l); i <= (r); ++i)
#define FF(i, r, l) for (int i = (r); i >= (l); --i)
#define MAX(a, b) ((a) = max(a, b))
#define MIN(a, b) ((a) = min(a, b))
#define SZ(a) ((int)((a).size()) - 1)

signed main(void)
{
	// freopen(".in", "r", stdin);
	// freopen(".out", "w", stdout);
	ios::sync_with_stdio(0), cin.tie(nullptr);

	int a, b;
	cin >> a >> b;
	int cl = 1, cr = 1000000, ans;
	while (cl <= cr)
	{
		int cm = (cl + cr) >> 1;
		int rem = max(0, a - cm * 3) + max(0, b - cm * 3),
			rs = cm + max(cm * 3 - max(a, b), 0);
		if (rem <= rs) ans = cm, cr = cm - 1;
		else cl = cm + 1;
	}
	cout << ans * 2 - 1 << '\n';
	
	return 0;
}