#include <iostream>
#include <fstream>
using namespace std;

int prim(int a,int b){
    while(a!=b){
        if(a>b) a=a-b;
        else b=b-a;
    }
    return a;}

int main()
{
fstream f,g;
f.open("fact.in",ios::in);
g.open("fact.out",ios::out);
int n,p=1,q,nr=0,n2=0,n5=0;
f>>n;
while(nr!=n){
    q=p;


        while(q%2==0){
        q=q/2;
        n2++;}
        while(q%5==0){
            q=q/5;
            n5++;
        }
        if(n2>n5) nr=n5;
        else nr =n2;

    p++;}

g<<p-1;
}