def insert_dash(num):
    num = str(num)
    dex = {i for (i, a) in enumerate(num) if (int(a) in ODD)}
    return ''.join((((b + '-') if {i, (i + 1)}.issubset(dex) else b) for (i, b) in enumerate(num)))
def insert_dash(num):
    num = str(num)
    dex = {i for (i, a) in enumerate(num) if (int(a) in ODD)}
    return .join((((b + '-') if {i, (i + 1)}.issubset(dex) else b) for (i, b) in enumerate(num)))