class Luke4 {
    static private var list = [Int]();
    static private var counter = 0;

    static private func isSpecial(n: Int) -> Bool {
        return n % 7 == 0 || String(n).contains("7");
    }

    static func solve() {

        for n in 1...1337 {
            if (isSpecial(n: n)) {
                list.append(list[counter]);
                counter += 1
            } else {
                list.append(n)
            }
        }
        print(list[1336])
    }
}