#include<fstream>
using namespace std;
int p,l1,l2,pp,n,z;
int aparitii(int n)
{
    int  puterea,ck;
    puterea=0;
    ck=5;
    while(n/ck>=1)
    {
        puterea=n/ck+puterea;
        ck=ck*5;
    }
    return puterea;
}
int main()
{
    ifstream f("fact.in");
    ofstream g("fact.out");
    f>>p;
    l1=1;
    l2=1000000000;
    pp=0;
    while(l1<=l2&& pp==0)
    {
        z=aparitii(n);
        if(z==p)
        {
            pp=1;
            n=n-n%5;
        }
        else
        if(z<p)
        l1=n+1;
        else
        l2=n-1;
    }
    if(pp==0)
        g<<"-1";
    else
        if(p==0) g<<"1";
        else g<<n;
    return 0;
}