/**

 * Created by YuKai Fan on 2018/9/5.

 */

public class MinStack{

    Stack<Integer> dataStack = new Stack<>();

    Stack<Integer> minStack = new Stack<>();

    public static void main(String[] args) {

        MinStack  minstack = new MinStack();

        minstack.push(5);

        minstack.push(7);

        minstack.push(3);

        minstack.push(4);

        /*System.out.println(minstack.pop());

        System.out.println(minstack.pop());*/

        System.out.println("min="+minstack.min());

    }

    public void push(int num) {

        dataStack.push(num);

        if (minStack.isEmpty() || num < minStack.peek()) {

            minStack.push(num);

        } else {

            minStack.push(minStack.peek());

        }

    }

    public void pop() {

        dataStack.pop();

        minStack.pop();

    }

    public int top() {

        return dataStack.peek();

    }

    public int min() {

        return minStack.peek();

    }

}