#include<bits/stdc++.h>
#define irep(i,l,r) for(int (i) = (l); (i) <= (r); ++(i))
#define drep(i,r,l) for(int (i) = (r); (i) >= (l); --(i))
#define ceil(pp,qq) (((pp)>0)^((qq)>0)?-abs(pp)/abs(qq):(pp)%(qq)?(pp)/(qq)+1:(pp)/(qq))
#define floor(pp,qq) (((pp)>0)^((qq)>0)?-ceil(abs(pp),abs(qq)):(pp)/(qq))
#define ll long long
#define LL __int128
using namespace std;

inline ll read(){
	char ch = getchar();
	ll s = 0; bool w = 0;
	while(!isdigit(ch)){if(ch == '-')w = 1;ch = getchar();}
	while(isdigit(ch))s = (s << 3) + (s << 1) + (ch ^ 48), ch = getchar();
	return w ? - s : s;
}

inline char rc(){
	char ch = getchar();
	while(1){
		if(ch >= 'A' && ch <= 'Z')return ch;
		if(ch >= 'a' && ch <= 'z')return ch;
		ch = getchar();
	}
}

template<class T1, class T2>
T1 min(T1 AA, T2 BB){return AA > BB ? BB : AA;}
template<class T1, class T2>
T1 max(T1 AA, T2 BB){return AA < BB ? BB : AA;}

const int itinf = 1e9;
const ll llinf = 4e18;
const int mod = 1000000007;
const int N = 500009;

int main(){
	int ad = read(), ch = read();
	int ans;
	for(ans = 1; ans <= ad + ch; ++ ans){
		int single = ans, dou = 3 * ans;
		int a = ad, c = ch;
		if(min(a,c) >= dou){
			int cc = min(a,c);
			a -= dou, c -= dou;
			if(single >= a + c){
				cout << ans * 2 - 1;
				return 0;
			}
		}
		else{
			if(dou + single >= max(a,c)){
				cout << ans * 2 - 1;
				return 0;
			}
		}
	}
	return 0;
}