fun countCharOccurrences(input: String, targetChar: Char): Int {
    return input.count { it == targetChar }
}

fun main() {
    val inputString = "Hello, world!"
    val targetChar = 'o'
    val occurrences = countCharOccurrences(inputString, targetChar)
    println("The character '$targetChar' occurs $occurrences times in the input string.")
}