Madison Bumgarner made sure the San Francisco Giants finished their long and strange series with Chicago Cubs on a winning note. Bumgarner pitched seven strong innings and Buster Posey went 4 for 4 with his 14th homer as the San Francisco Giants topped the Chicago Cubs for a 5-3 victory on Thursday night. ''He's as mentally tough as you get,'' said Giants manager Bruce Bochy about his young pitcher. ''He's got a knack for making pitches when he has to.'' Pablo Sandoval added three hits and two RBIs as the Giants rebounded from a 2-1 loss earlier in the day in the resumption of their suspended game in the series opener.