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

let a = readInts()
let b = readInts()
let t = Int(readLine()!)!

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

