Решение

import java.io.BufferedReader
import java.io.BufferedWriter
import java.io.InputStreamReader
import java.io.OutputStreamWriter

fun main() {
    val reader = BufferedReader(InputStreamReader(System.`in`))
    val writer = BufferedWriter(OutputStreamWriter(System.out))
    val numbers = reader.readLine().split(" ").map(String::toInt).toSet()
    writer.write(numbers.size.toString())
    reader.close()
    writer.flush()
    writer.close()
}