#include <fstream>

using namespace std;

ifstream fin("fact.in");
ofstream fout("fact.out");

int p,n=1220703125;
int nr0(int n)
{
    int x=0;
    while(n)
        x+=n/5,n/=5;
    return x;
}
int cauta(int p)
{
    int s=1, d=n, m, N=-1;
    while(s<=d)
    {
        m=(s+d)/2;
        if(nr0(m)>=p)N=m, d=m-1;
        else s=m+1;
    }
    return N;
}
int main()
{
    fin>>p;
    int n=cauta(p);
    if(nr0(n)==p)
        fout<<n;
    else fout<<-1;
    return 0;
}