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

//--------------------------------
// #define int long long
#define LL long long
// #define lc p << 1
// #define rc p << 1 | 1
#define lowbit(x) x & (-x)
#define nc() (p1 == p2 && (p2 = (p1 = buf) + fread(buf, 1, 100000, stdin), p1 == p2) ? EOF : *p1++)
// #pragma GCC optimize(2)
#define Blizzard ios::sync_with_stdio(0), cin.tie(0), cout.tie(0)

inline void read(LL &a)
{
    LL s = 0, w = 1;
    char ch = getchar();
    while (ch < '0' || ch > '9')
    {
        if (ch == '-')
            w = -1;
        ch = getchar();
    }
    while (ch >= '0' && ch <= '9')
    {
        s = s * 10 + ch - '0';
        ch = getchar();
    }
    a = s * w;
}
//-----------------------------------------
void solve()
{
    int n, m;
    cin >> n >> m;
    if (n == 0 && m == 0)
    {
        cout << 0;
        return;
    }
    int cnt = 0;
    int t1 = n / 4;
    if (n % 4)
        t1++;
    int t2 = m / 3;
    if (m % 3)
        t2++;
    if (t1 >= t2)
    {
        cnt = n / 4;
        if (n % 4)
            cnt++;
        cout << 2 * cnt - 1;
        return;
    }
    while (n - 3 > 0 && m - 4 >= 0)
    {
        n -= 3;
        m -= 4;
        cnt++;
    }
    // cout << n << " " << m << endl;
    if (n - 3 <= 0 && m - 4 <= 0)
    {
        cnt++;
        cout << 2 * cnt - 1;
        return;
    }
    else if (n - 3 <= 0 && m - 4 > 0)
    {
        cnt += m / 4;
        if (m % 4)
            cnt++;
        cout << 2 * cnt - 1;
    }
    else if (n - 3 > 0 && m - 4 <= 0)
    {
        cnt += n / 4;
        if (n % 4)
            cnt++;
        cout << 2 * cnt - 1;
    }
}

signed main()
{
    Blizzard; // false
    int _ = 1;
    // cin >> _;
    while (_--)
        solve();
    return 0;
}
/*
while (l < r)
    {
        int mid = l + r >> 1;
        if (check(mid)) r = mid;
        else l = mid + 1;
    }
*/