fun fib (n: Int): Int = fibCache.getOrPut (n) {
    fib (n - 1) + fib (n - 2)
}

val fibCache = mutableMapOf (0 to 0, 1 to 1)

fun main () {
    generateSequence (::readlnOrNull).forEach {
        println (fib (it.toInt ()))
    }
}