#include <iostream>
#include <fstream>
#include <math.h>
using namespace std;
ifstream fin("fact.in");
ofstream fout("fact.out");
long long int p,n=0;
int putere5(long long int k)
{
    int k1=0;
    while(k%5==0)
    {
        k1++;
        k=k/5;
    }
    return k1;
}
int main()
{

    fin>>p;
    long long int i,j,p5;
    if(p==0)
        fout<<1;
        else
     {
        for(i=1;i<=p&&n<p;i++)
            if(i%5!=0)
        {n=n+1;
        p5=i;}
        else
        {
           n=n+putere5(i)+1;
           p5=i;

        }
              if(n==p)
                fout<<p5*5;
              else
                fout<<-1;
     }

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