#include <fstream>

using namespace std;

ifstream fin("fact.in");
ofstream fout("fact.out");

int nrdivp(int x){
    int hehe = 0, idk = 5;
    while(idk <= x){
        hehe += x / idk;
        idk *= 5;
    }

    return hehe;
}

int main()
{
    int n;
    fin >> n;

    int rez = 0, lol;

    for(int p = (1<<30); p > 0; p>>=1){
        lol = nrdivp(rez + p);
///        fout << lol << endl;
        if(lol < n){
///            fout << endl << p << endl << endl;
///            if(nrdivp(rez + p - 1) < n) rez -= p;
///            else rez += p;
///            fout << lol << ' ' << rez << endl;
            rez += p;
        }
    }
    rez++;
    if(nrdivp(rez) != n) rez = -1;

    fout << rez;
}