#include <fstream>
#include <iostream>

using namespace std;

ifstream q("fact.in");
ofstream w("fact.out");

int put5(long long n)
{
    int put=0,a=5;
    while(1)
    {
        if(n%a==0)
        {
            put++;
            a*=5;
        }
        else return put;
    }
}

int main()
{int p,z;
    long long n;
    q>>p;
    if(p==0)
        {w<<"1";return 0;}
    z=0;
    n=0;
    do
    {
        n+=5;
        z+=put5(n);
    }while(z<p);
    w<<n;

    return 0;
}