#include <iostream>
#include <fstream>
using namespace std;
ifstream in("fact.in");
ofstream out("fact.out");
int main()
{
    int n,p=0;
    in>>n;
    int ind=0;
    if(!n){
        out<<1;
    }
    else {
        while(n>p){
            int q=ind;
            while(q){
                if(q%5==0){
                    q/=5;
                    p++;
                }
                else{
                   q=0;
                }
            }
            ind+=5;
        }
        out<<ind-5;
    }
    return 0;
}