// #pragma GCC optimize("O3")
// #pragma GCC optimize("Ofast")
// #pragma GCC optimize("unroll-loops")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,tune=native")
#include <bits/stdc++.h>
using namespace std;

#define PB emplace_back
// #define int long long
#define ll long long
#define vi vector<int>
#define siz(a) ((int) ((a).size()))
#define rep(i, a, b) for (int i = (a); i <= (b); ++i)
#define per(i, a, b) for (int i = (a); i >= (b); --i)
void print(vi n) {rep(i, 0, siz(n) - 1) cerr << n[i] << " \n"[i == siz(n) - 1];}

int a, b;

signed main() {
	// freopen(".in", "r", stdin);
	// freopen(".out", "w", stdout);
	ios::sync_with_stdio(0);
	cin.tie(0), cout.tie(0);
	cin >> a >> b;
	rep(i, 1, 1e6) {
		a -= 3, b -= 3;
		if(a > b) --a;
		else --b;
		if(a <= 0 && b <= 0) return cout << i * 2 - 1, 0;
	}
	return cerr << endl << 1.0 * clock() / CLOCKS_PER_SEC << endl, 0;
}