import java.io.PrintWriter import java.util.* import kotlin.math.* fun PrintWriter.solve() { val s = nextLine() val t = s.reversed() if (s != t) { println(s.length) } else if (s.toCharArray().distinct().count() > 1) { println(s.length - 2) } else if (s.length % 2 == 0) { println(0) } else { println(-1) } } fun main() { val writer = PrintWriter(System.out, false) writer.solve() writer.flush() } // 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