A first-half penalty from Paul McManus and a Scott McBride strike gave Arbroath a 2-1 win over Nairn County in the Scottish Cup.Arbroath eased into the fourth round and McManus set them on their way in the 22nd minute after Simon Murray was felled inside the area by Wayne Mackintosh.McManus found the bottom-left corner with the resulting spot-kick as the home team controlled the game, and they could have been further ahead but for the excellent Calum Antell in the Nairn goal.The visitors had a goal disallowed in the second half and were soon two down as McBride headed home from inside the area after 65 minutes.Sean Webb scrambled home a late goal to give some hope to the Highland league side, but they were unable to draw level.