#include<iostream>
#include<fstream>
using namespace std;
int main()
{
    int n,p,i,d,e,a,b,c;
    fstream f("factorial.in",ios::in);
    fstream g("factorial.out",ios::out);
    f>>p;
    d=0;
    c=0;
    i=0;
    if(p!=0)
    while((d<p)||(c<p))
    {
        i++;
        e=1;
        a=2;
        while(e==1)
        if(i%a==0) {d++;a=a*2;}
           else e=0;
        a=5;
        e=1;
        while(e==1)
        if (i%a==0) {c++;a=a*5;}
            else e=0;
    }
    else i=1;
    g<<i;
    f.close();
    g.close();
}