class MinStack {
    private Stack<Integer> stack;
    private Stack<Integer> minStack;
    
    public MinStack() {
        stack = new Stack<>();
        minStack = new Stack<>();
    }
    
    public void push(int val) {
        stack.push(val);
        if (minStack.isEmpty() || val <= minStack.peek()) {
            minStack.push(val);
        } else {
            minStack.push(minStack.peek());
        }
    }
    
    public void pop() {
        if (!stack.isEmpty()) {
            stack.pop();
            minStack.pop();
        }
    }
    
    public int top() {
        return stack.peek();
    }
    
    public int getMin() {
        return minStack.peek();
    }
}

// One stack solution
class MinStack2 {
    private Stack<Integer> stack;
    private int min;
    
    public MinStack2() {
        stack = new Stack<>();
        min = Integer.MAX_VALUE;
    }
    
    public void push(int val) {
        if (val <= min) {
            stack.push(min);
            min = val;
        }
        stack.push(val);
    }
    
    public void pop() {
        if (stack.pop() == min) {
            min = stack.pop();
        }
    }
    
    public int top() {
        return stack.peek();
    }
    
    public int getMin() {
        return min;
    }
}