#include<iostream>

using namespace std;

int ms=0;

int namestvane(int a, int b, int r, int k, int s)
{
   int ts; 
   ts=s+2;
   
   if(ts>=ms)
   ms=ts;
   if((a>2)&&(b>2))
   {
   namestvane(a-r,b-k,1,2,ts);
   namestvane(a-r,b-k,2,1,ts);
   }
   else
   {
      ts=ts+2;
   }
}


int main()
{
    int x,y;
    cin>>x>>y;
    
    namestvane(x,y,1,2,0);
    namestvane(x,y,2,1,0);
    
    cout<<ms;
    
//    system("pause");
     
}
