#include <fstream>
using namespace std;
long p, k, i, aux;
int n;
int main()
{
    ifstream fin("fact.in");
    ofstream fout("fact.out");
    fin>>n;
    fin.close();
    if(n==0)
    {
        fout<<"1";
        fout.close();
    }
    else
    {
        k=0;i=1;
        while(k<n)
        {
            aux=i;
            while(aux%5==0)
            {
                k++;
                aux/=5;
            }
            i++;
        }
        if(k==n)
            fout<<i-1;
        else
            fout<<"-1";
    }
    fout.close();
    return 0;
}