#include<fstream>
using namespace std;
ifstream f("pascal.in");
ofstream g("pascal.out");
unsigned long long n,d,sol,i,k,ok;
unsigned long long comb[5000001];
int main()
{
    f>>n>>d;
    ok=0;
    for(i=1;i<=n/2;i++)
        if(n%i==0)
        ok=1;
        if(!ok)
            g<<n-1;
        else

        {
    comb[0]=1;
    comb[1]=n;
    if(n%d==0)
        sol++;
    if(n%2==0)
    for(i=2;i<=n/2;i++)
    {
        comb[i]=(((n-i+1)*comb[i-1])/i);
    if(comb[i]%d==0)
       {
           sol=n/2+1-i+1;
           break;
       }
    }
    else
        for(i=2;i<=n/2+1;i++)
    {

        comb[i]=(((n-i+1)*comb[i-1])/i);
        //g<<comb[i]<<" ";
    if(comb[i]%d==0)
        {
        sol=n/2+1-i+1;
            break;
        }
    }
    if(n%2==0)
    g<<2*sol-1;
    else
    g<<2*sol;
        }
}