_ = readLine()!
var a = readLine()!.split(separator: " ").compactMap { Int($0) }

let minusCount = a.lazy.filter { $0 < 0 }.count

if minusCount % 2 == 0 {
    print(a.lazy.map(abs).reduce(0, +))
} else {
    let sorted = a.lazy.map(abs).sorted()
    let head = sorted.first!
    let tail = sorted.lazy.dropFirst()
    print(tail.reduce(-head, +))
}
