import java.io.PrintWriter import java.util.* import kotlin.math.* fun PrintWriter.solve() { val s = nextLine() val a = s.count { it == 'a' } println("a".repeat(a + 1)) } fun main() { Thread(null, { val writer = PrintWriter(System.out, false) writer.solve() writer.flush() }, "solve", 1.shl(26)).start() } // region Scanner private var st = StringTokenizer("") private val br = System.`in`.bufferedReader() fun next(): String { while (!st.hasMoreTokens()) st = StringTokenizer(br.readLine()) return st.nextToken() } fun nextInt() = next().toInt() fun nextLong() = next().toLong() fun nextLine() = br.readLine() fun nextDouble() = next().toDouble() // endregion