import java.util.Stack;

class MinStack {
    private Stack<Integer> dataStack;  // 数据栈
    private Stack<Integer> minStack; // 辅助栈，放入最小元素
    /** initialize your data structure here. */
    public MinStack() {
        dataStack = new Stack<>();
        minStack = new Stack<>();
    }

    public void push(int x) {
        dataStack.push(x);
        // 如果x小于等于minstack的栈顶
        if (minStack.isEmpty() || minStack.peek() >= x) minStack.push(x);
    }

    public void pop() {
        int x = dataStack.pop();
        if(x == minStack.peek()) minStack.pop();
    }

    public int top() {
        return dataStack.peek();
    }

    public int getMin() {
        return minStack.peek();

    }

}