#include <iostream>
#include <fstream>
using namespace std;
ifstream fin("fact.in");
ofstream fout("fact.out");

unsigned long long n,i,p,S;

int main()
{
    fin>>n;
    i=0;
    p=0;
    while(p<=n)
    {
        i=S+5;
        S=i;
        while(i%5==0)
        {
            i=i/5;
            p++;
        }
    }
    cout<<S-5;
    return 0;
}