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


int main()
{
    int n;
    in>>n;
    if(n==0)
        out<<1;
    int i=5,nrz=0;
    while(n!=0&&nrz<n)
    {
        nrz++;
        int c=i;
        c=c/5;
        while(c%5==0)
        {
            nrz++;
            c=c/5;
        }
        i+=5;
    }

    out<<i-5;
}