#include <iostream>
#include <cstring>
using namespace std;
int main()
{
int n,i,k;
int *a,*b;
while(cin>>n)
{
a=new int[2*n+1];
b=new int[2*n+1];
for(i=0;i<2*n+1;i++)
a[i]=b[i]=0;
a[n]=1;
for(k=1;k<n;k++)
{
if(k%2==1)
{
for(i=1;i<2*n;i++)
b[i]=a[i-1]+a[i]+a[i+1];
}
else
{
for(i=1;i<2*n;i++)
a[i]=b[i-1]+b[i]+b[i+1];
}
}
k=0;
if(n%2==1)
{
for(i=1;i<2*n+1;i++)
{
if(a[i]!=0&&a[i]%2==0)
{
cout<<i<<endl;
k=1;
break;
}
}
}
else
{
for(i=0;i<2*n+1;i++)
{
if(b[i]!=0&&b[i]%2==0)
{
cout<<i<<endl;
k=1;
break;
}
}
}
if(k==0)
cout<<-1<<endl;
delete a;
delete b;
}
return 0;
}