#include <fstream>
#include <climits>
using namespace std;
ifstream cin ("fact.in");
ofstream cout ("fact.out");
int nrzero (int x)
{
    int s=0;
    while(x!=0)
    {
        x=x/5;
        s+=x;
    }
    return s;
}
int main()
{
    int st,dr,mij,nr,p,ans;
    cin>>p;
    st=1;
    dr=INT_MAX-1;
    while(st<=dr)
    {
        mij=(st+dr)/2;
        nr=nrzero(mij);
        if(nr<p)
            st=mij+1;
        else
        {
            dr=mij-1;
            ans=mij;
        }
    }
    if(nrzero(ans)==p)
            cout<<ans;
    else
        cout<<-1;
    return 0;
}