import Foundation
func readInts() -> [Int] {
    return readLine()!.components(separatedBy: " ").map { Int($0)! }
}

break_label: do {
    let a = readInts()
    let b = readInts()
    let t = Int(readLine()!)!

    if a[0] > b[0] {
        print("NO")
        break break_label
    }

    print(a[0] + a[1]*t >= b[0] + b[1]*t ? "YES" : "NO")
}
