#include <fstream>

using namespace std;

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

long long zerouri(long long n) {
    long long nrzero = 0;
    while (n != 0) {
        n /= 5;
        nrzero++;
    }
    return nrzero;
}
int main() {
    long long P;
    fin >> P;
    if (P == 0) {
        fout << 1;
        return 0;
    }
    long long st = 1;
    long long dr = 5 * P;
    long long rasp = -1;
    while (dr >= st) {
        long long suma = st + dr;
        long long mijloc = suma / 2;
        if (zerouri(mijloc) < suma)
            st = mij + 1;
        else {
            rasp = mijloc;
            dr = mijloc - 1;
        }
    }
    if (zerouri(rasp) == P)
        fout << rasp;
    else
        fout << -1;
}