include <bits/stdc++.h>

using namespace std; bool number (int x){

int a=2;
while (x%a!=0)
a++;
if (a==x)
return true;
else
return false;

}

int main (){

int a;
cin>>a;
if (number (a)==1)
cout<<"1";
else
cout<<"-1";
return 0;

}