Swimmer Lukas Märtens has claimed the first gold and overall medal for Germany at the Paris Olympics in the men’s 400-metre freestyle on Saturday. The 22-year-old set the fastest time of 3 minutes 41.78 seconds, beating Elijah Winnington of Australia by 0.43 seconds. Kim Woo-min of South Korea took bronze, 0.72 seconds off the pace. Märtens had topped the timesheets in the heats earlier. His previous biggest success had been a silver at the 2022 world championships. In the women’s 100m butterfly, Gretchen Walsh of the United States advanced to the final by setting a new Olympic record with the…