栈

public class MyStack {
    private long[] arr;
    private int top;

    public MyStack(){
        arr = new long[10];
        top = -1;
    }

    public MyStack(int max){
        arr = new long[max];
        top = -1;
    }

    public void push(int value){
        arr[++top]=value;
//        top++;
//        arr[top]=value;
    }

    public long pop(){
//        top--;
//        return arr[top+1];
        return arr[top--];
    }

    public long peek(){
        return arr[top];
    }

    public boolean isEmpty(){
        return top==-1;
    }


}