#include <iostream>
#include <fstream>
using namespace std;
ifstream f("fact.in");
ofstream g("fact.out");
long long n,ra,rez=10000000000LL,num;
int verif(long long nr)
{
    long long d=1,c=0;
    while(nr/d)
    {
        d=d*5;
        c+=nr/d;
    }
    if(c==n)
        num=nr;
    if(c>=n)
        return 1;
    else
        if(c<n) return 0;
}
long long caut_bin()
{
    long long st,dr=10000000000LL,mij;
    st=1;
    while(st<=dr)
    {
        mij=(st+dr)/2;
        ra=verif(mij);
        if(ra==1) dr=mij-1;
        else st=mij+1;
    }
    return st;
}
int main()
{
    f>>n;
    if(caut_bin()==num) g<<num;
    else g<<-1;
    return 0;
}