function Main(input) {
    input = input.split("\n").map(i => parseInt(i, 10))

    const limit = input.pop()

    const diffsMax = input.map(i => {
        var diffs = input.map(j => {
            return Math.abs(i-j)
        })
        return Math.max(...diffs) 
    })

    const maxDistance = Math.max(...diffsMax)
    const result = (maxDistance > limit) ?  ':(' : 'Yay!' 
    console.log(result )
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"))