import Foundation

func solution(_ k:Int, _ m:Int, _ score:[Int]) -> Int {
    let sort: [Int] = score.sorted(by: >)
    return stride(from: m - 1, to: sort.count, by: m).reduce(0){ $0 + sort[$1] * m }
}

print(solution(3, 4, [1, 2, 3, 1, 2, 3, 1])) // 8
print(solution(4, 3, [4, 1, 2, 2, 4, 4, 4, 4, 1, 2, 4, 2])) // 33