#include <iostream>
#include <fstream>
using namespace std;
ifstream fin("fact.in");
ofstream fout("fact.out");
int main()
{
    int p,x=0;
    fin>>p;
    int cp=p;
    while(p>0)
    {
        x+=5;
        int c=x;
        while(c%5==0&&c!=0)
        {
            c=c/5;
            p--;
        }
    }
    if(cp!=0)
    {
        fout<<x;
    }
    else
    {
        fout<<1;
    }
    return 0;
}