#include <iostream>
#include <fstream>
using namespace std;
long long p,a,b,m,x,c;
ofstream g("fact.out");
int main()
{
    freopen("fact.in","r",stdin);
    scanf("%d",&p);
    a=1;
    b=1000000000;
    while(a<=b)
    {
        m=(a+b)/2;
        x=m;
        c=0;
        while(m!=0)
        {
            c=c+m/5;
            m=m/5;
        }
        if(c==p)
        {
            if(x-x%5==0)
                g<<"1";
            else
                g<<x-x%5;
            b=-1;

        }
        else
            if(c<p)
                a=(a+b)/2+1;
                else b=(a+b)/2-1;


    }
    if(b!=-1)
        g<<"-1";
}