#include <fstream>
using namespace std;

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

int n;

int Nrzero(int n)
{
    int s = 0;
    int c = 5;
    while ( c <= n)
    {
        s+=n/c;
        c*=5;
    }
    return s;
}

int C_b(int ls, int ld)
{

    int m;
    while ( ls <= ld)
    {

        m = (ls+ld)/2;
        if ( Nrzero(m) == n)
            return m;
        if ( Nrzero(m) < n)
            ls = m+1;
        else
            ld = m-1;
    }
}

int main()
{
    fin >> n;
    if ( n == 0)
        fout << 1;
    else
    {


    int nr = C_b(1, 100000000);
    nr = nr - nr % 5;
    fout << nr;
    }
    fin.close();
    fout.close();
    return 0;
}