The Raiders returned home to face the San Diego Chargers in their first division game of the season. However, the Raiders offense struggled to score early, unable to score a touchdown on three offensive possessions in Charger territory in the first half and turning the ball over early. Derek Carr was picked on the fourth play from scrimmage, setting up the Chargers for a chance to take an early lead. However, the Raiders defense forced a fumble and prevented the Chargers from scoring. The Raiders offense could not take advantage, only managing three field goals in the first half by Sebastian Janikowski, however he missed a fourth attempt. Tyrell Williams scored for the Chargers on a 29-yard pass from Philip Rivers and the Chargers took a 10-9 lead into the half. In the second half, the Chargers took a 17-9 lead on Melvin Gordon reception from Rivers. The Raiders answered on a 64-yard pitch and catch from Carr to Amari Cooper, his first touchdown catch of the year. However, the Raiders defense continued its struggles, giving up another touchdown pass from Rivers to Hunter Henry as the Raiders fell behind 24-16. A 48-yard field goal by Janikowski brought the Raiders within five before the Raider defense garnered its third turnover of the game, forcing a Gordon fumble. The Raider offense struggled in response and were left with a fourth and two from the Charger 21-yard line. Continuing with the season's gutsy calls, head coach Jack Del Rio went for it and Carr found Michael Crabtree for a diving catch in the corner of the endzone to give the Raiders their first lead of the game. The Raiders added on from there, scoring a touchdown on a Jamize Olawale one-yard run seemingly salting the game away, 34-24. However, the Raider defense allowed the Chargers to move within three on a 76-yard drive capped by an Antonio Gates touchdown catch. Trailing 34-31, the Charges again moved into Raider territory in the waning seconds of the fourth quarter. Forced to attempt a game-tying field goal, the Chargers fumbled the snap and the Raiders were able to run out the clock. Moving to 4-1 on the season, the first time since 2002, the Raider defense still surrendered over 400 yards for the fourth time in five games this season. Del Rio was angered by the continued poor defensive showing. Despite this and combined with a loss by the Denver Broncos, the Raiders moved into a tie for first place in the AFC West.

Based on the above article, answer a question. How many field goals did Sebastian Janikowski attempt in the first half?
4