// what is matter? never mind. 
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
//#pragma GCC target("sse,sse2,sse3,sse4,popcnt,abm,mmx,avx,avx2") 
#include<bits/stdc++.h>
#define For(i,a,b) for(int i=(a);i<=(b);++i)
#define Rep(i,a,b) for(int i=(a);i>=(b);--i)
#define ll long long
#define ull unsigned long long
//#define int long long
using namespace std;
inline int read()
{
    char c=getchar();int x=0;bool f=0;
    for(;!isdigit(c);c=getchar())f^=!(c^45);
    for(;isdigit(c);c=getchar())x=(x<<1)+(x<<3)+(c^48);
    if(f)x=-x;return x;
}

#define fi first
#define se second
#define pb push_back
#define mkp make_pair
typedef pair<int,int>pii;
typedef vector<int>vi;
 
#define maxn 500005
#define inf 0x3f3f3f3f



signed main()
{
	int n=read(),m=read();
	int l=1,r=3e6,res=3e6;
	while(l<=r){
		int mid=l+r>>1;
		int nn=max(0,n-mid*3);
		int mm=max(0,m-mid*3);
		if(nn+mm<=mid) res=mid,r=mid-1;
		else l=mid+1;
	}
	cout<<res*2-1;
    return 0;
}
/*
5 10 5
01234
0 1

01234

*/