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