Section 18. Whoever, in the night time, enters a dwelling house without breaking, or breaks and enters in the day time a building, ship or motor vehicle or vessel, with intent to commit a felony, no person lawfully therein being put in fear, shall be punished by imprisonment in the state prison for not more than ten years or by a fine of not more than five hundred dollars and imprisonment in jail for not more than two years. Whoever commits any offense described in this section while armed with a firearm, rifle, shotgun, machine gun or assault weapon shall be punished by imprisonment in the state prison for not less than five years or by imprisonment in the house of correction for not more than two and one-half years.