#include <fstream>
#include <math.h>
using namespace std;
ifstream fin("factorial.in");
ofstream fout("factorial.out");
int p,k,n,x;
int verif5(int n){
    if(n==0)
        return 1;
    int p=0;
    while(n!=1)
        if(n%5==0){
            n=n/5;
            p++;}
        else return 1;
    return p;}
int main(){
    int i;
    fin>>p;
    if(p==0)
        fout<<1;
    while(p>0){
        k=verif5(x);
        x+=5*k;
        p=p-k;}
    fout<<x;
    return 0;
    }