fun main() {
    val builder = StringBuilder()

    val s = readInputLine()

    for (i in 'a'..'z') {
        if (s[i - 'a'] != i) {
            builder.appendln("${i}to${s[i - 'a']}")
            break
        }
    }

    print(builder.toString())
}

fun readInputLine(): String {
    return readLine()!!
}