#include <fstream>

using namespace std;
ifstream in ("fact.in");
ofstream out ("fact.out");
int main()
{
    int n=0,p,cnt=0,cn;
    in>>p;
    if(p==0) out<<1;
    else
    {
        while(p!=cnt)
        {
            n++;
            if(n%5==0)
            {
                cn=n;
                while(cn%5==0)
                {
                    cn=cn/5;
                    cnt++;
                }
                if(cnt==p) break;
            }
        }
         if(cnt!=p) out<<-1; else out<<n;
    }
        return 0;
    }