fun main() {
    val input = generateSequence(::readLine)
        .map { it.split(")") }
        .groupBy { it[0] }
        .mapValues{ it.value.map { it[1] } }
    val rootNode = input.keys - input.values.flatten().toSet()
    
    println("Part 1: ${countOrbiters(input, rootNode.first(), 0)}")
}

fun <T>countOrbiters(graph: Map<T, List<T>>, key: T, acc: Int): Int {
    return acc + (graph[key]?.map { countOrbiters(graph, it, acc+1) }?.sum() ?: 0)
}