#include<iostream>
#include<fstream>
#include<vector>
using namespace std;
ifstream in("fact.in");
ofstream out("fact.out");
long long count_dem_zeros (long long a)
{
    long long i=5,nr=0;
    while(i<=a)
    {
        nr+=a/i;
        i*=5;
    }
    return nr;
}
long long cauarebinara0(long long k)
{
    long long  step=2<<27;
    long long  sol=0;
    for(; step>=1; step=step/2)
       if(count_dem_zeros(step+sol)<k)
          sol=step+sol;
    return sol+1;
}
int main()
{
    long long  n;
    in>>n;
   long long f=cauarebinara0(n);
    if(count_dem_zeros(f)==n)
        out<<f;
    else
        out<<"-1";
}