#include <iostream>
#include <fstream>
#include <math.h>

using namespace std;

ifstream fin("fact.in");
ofstream fout("fact.out");

int main() {

    long long i,p,div,nr;
    fin>>p;
    for(i=5;div<=p;i+=5)
    {
        nr=i;
        while(nr%5==0)
        {
            div++;
            nr=nr/5;
        }
    }
    if(p==0)
        cout<<"1";
    else
        cout<<i-10;
    fin.close();
    fout.close();

    return 0;
}