#include <iostream>
#include <algorithm>
using namespace std;
int main()
{
 int  n,m,br=0,d1,d2,d3,d4,p,fl=0,fl1=0,fl2=0,fl3=0,fl4=0;
 cin>>n>>m;
 d1=1;
 d2=m;
 d3=m*m+1;
 d4=n*m;
 p=1+m+1;
 while((p!=d1)&&(p!=d2)&&(p!=d3)&&(p!=d4))
 {
	while(p%m!=0 && p+(m+1)<=n*m)
	{if((p!=d1)&&(p!=d2)&&(p!=d3)&&(p!=d4))
	  p=p+(m+1);
	 else
	  break;
	 fl=1;
	 fl1=1;
	}
	if(fl==1)
	{
	 br++;
     fl=0;
	}
	/*cout<<p<<" 1"<<endl;*/
	if(fl4==0)
	while(p+m-1<=n*m)
	{if((p!=d1)&&(p!=d2)&&(p!=d3)&&(p!=d4))
	  p=p+(m-1);
	 else
	  break;
	 fl=1;
	 fl2=1;
	}
    fl4=0;
	/*cout<<p<<" 2"<<endl;*/
	if(fl==1)
	{
	 br++;
	 fl=0;
	}
	if((fl1==0 && fl2==1) || (fl1==1 && fl2==1))
    while(p%m!=1)
    {if((p!=d1)&&(p!=d2)&&(p!=d3)&&(p!=d4))
	  p=p-(m+1);
	 else 
	  break;
	 fl=1;
    }
	if(fl==1)
	{
	 br++;
	 fl=0;
	}
	/*cout<<p<<" 3"<<endl;*/
	while(p-(m-1)>0 && p%m!=0)
	{if((p!=d1)&&(p!=d2)&&(p!=d3)&&(p!=d4))
	  p=p-(m-1);
	 else
	  break;
	 fl=1;
	 fl4=1;
	}
	if(fl==1)
	{
	 br++;
	 fl=0;
	}
  /*cout<<p<<" 4"<<endl;*/
  fl1=0;
  fl2=0;
 }
cout<<br<<endl;
 return 0;
}
