import java.util.Stack
fun main() {
val stack = Stack<Int>()
stack.push(10)
stack.push(20)
stack.push(30)
stack.push(40)
println("Top element: ${stack.peek()}")
println("Popped element: ${stack.pop()}")
println("Stack after pop: $stack")
}
/*
run:
Top element: 40
Popped element: 40
Stack after pop: [10, 20, 30]
*/