func checkHitachi(str: String) -> Bool {
    let arr = Array(str)
    for (i, value) in arr.enumerated() {
        if i % 2 == 0 {
            if value != "h" {
                return false
            }
        } else {
            if value != "i" {
                return false
            }
        }
    }
    return true
}