#include<iostream.h>
#include<fstream.h>
int main ()
{
ifstream x("fact.in");
ofstream q("fact.out");
unsigned long p,a=0,b=32000,c;
unsigned int ok=0;
x>>p;
do
{
ok=1;
c=(a+b)/2;
if(c%p==0)
{
ok=1;
q<<c;
}
else
{
if(c<p)
{
a=c+1;
}
else
{
b=c-1;
}}
}
while(ok!=1);
if(ok==0)
{
q<<-1;
}
x.close();
q.close();
return 0;
}