import Foundation

func readInt() -> Int {
    return Int(readLine()!)!
}

func readInts(separator: String.Element = " ") -> [Int] {
    return readLine()!.split(separator: separator).map { Int($0)! }
}

func readThreeInts(separator: String.Element = " ") -> (a: Int, b: Int, c: Int) {
    let ints = readLine()!.split(separator: separator).map { Int($0)! }
    return (a: ints[0], b: ints[1], c: ints[2])
}

func mainB() {
    let (A, B, C) = readThreeInts()
    let K = readInt()

    for i in 0...K {
        let Bd = B * max(2 * (K - i), 1)
        let Cd = C * max(2 * i, 1)

        if A < Bd, Bd < Cd {
            print("Yes")
            return
        }
    }

    print("No")
}

mainB()