#include <fstream>

using namespace std;

ifstream fin("fact.in");
ofstream fout("fact.out");

int main()
{
    int p;
    fin>>p;
    if (p==0) fout<<"1";
    else if (p!=0 && p%5==0 && p%10!=0) fout<<"-1";
         else if (p%5!=0 && p!=0) fout<<p*5;
              else fout<<(p-(p-1)/5)*5;


    //(p/25+p/125+p/625+p/3125+p/15625+p/78125+p/390625+p/9765625+p/48828125);


    fin.close();
    fout.close();
    return 0;
}