#include <fstream>

using namespace std;

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

const int L = 20;

int nrzero(int n){
    int nr = 0;
    while(n >= 5){
        nr += n / 5;
        n /= 5;
    }
    return nr;
}

int main()
{
    int r, pas, p;
    fin >> p;
    r = 0;
    pas = 1 << L;
    while(pas != 0){
        if(nrzero(r + pas) < p){
            r += pas;
        }
        pas /= 2;
    }
    r++;
    if(nrzero(r) != p){
        r = -1;
    }
    fout << r;

    return 0;
}