#include <iostream>
#include <fstream>

using namespace std;

ifstream f("fact.in");
ofstream g("fact.out");

long long p,nr=0;
int main()
{
    f>>p;
    for(long i=1;i<=p;i++)
    {
        long x=i;
        while(x%5==0)
        {
            p--;
            x=x/5;
        }
    }
    p=p*5;
    if(p!=0)
        g<<p;
    else
        g<<"1";
}