//思路：入栈时不是最小值，永远都没机会成为最小值。

import java.util.Stack;

class MinStack {

    private Stack<Integer> stack = new Stack<Integer>();

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

    public void push(int x) {

		stack.push(x);

		if(!minStack.empty())

		{

			int min = minStack.peek();

			if(x <= min)

			{

				minStack.push(x);

			}

		}

		else

		{

			minStack.push(x);

		}

    }

    public void pop() {

    	if(minStack.size() != 0 && ((int)stack.peek() == (int)minStack.peek()))

        {

        	minStack.pop();

        }

    	stack.pop();

    }

    public int top() {

        return (int)stack.peek();

    }

    public int getMin() {

        return (int)minStack.peek();

    }

}