#include <iostream>
#include <fstream>
#include <cmath>

using namespace std;

int nrzerouri(int k){
    if(k>0)
        return 5*nrzerouri(k-1) + 1;
    return 1;
}

int main(){
    ifstream f("fact.in");
    int P, nr=0;
    f>>P;
    f.close();

    int sum=0;
    while(P>0){

            int y=(log((double)P)/log(5.0));
            int x= nrzerouri(y);
            sum += (int)(P/x) * pow(5,y);
            P= P%x;

            }


    ofstream g("fact.out");
    if(sum==0)
        g<<1;
    else g<<sum*5;
    g.close();

    return 0;

    }