#include <fstream>

using namespace std;

#define INFILE "fact.in"
#define OUTFILE "fact.out"

ifstream fin (INFILE);
ofstream fout (OUTFILE);

typedef long long ll;

const ll MAX = 1e18;

ll nr;

ll nrCifre(ll numar){

    ll rezultat = 0;

    while(numar){

        rezultat += numar / 5;

        numar /= 5;

    }

    return rezultat;

}

void solve(){

    fin >> nr;

    ll st = 1, dr = MAX;

    while(st < dr){

        ll mij = (st + dr) / 2;

        if(nrCifre(mij) < nr){
            st = mij + 1;
        }
        else{
            dr = mij;
        }

    }

    if(nrCifre(st) == nr){
        fout << st << '\n';
    }
    else{
        fout << -1 << '\n';
    }

}

int main(){
    solve();
    return 0;
}