This is from leetcode question 155. Min Stack

The getMin() function returns incorrect answer in a particular testcase and i don’t understand why!

     class MinStack {
        static ArrayList<Integer> stack = new ArrayList<Integer>();
        static ArrayList<Integer> minStack = new ArrayList<Integer>();

        public MinStack() {

        }

        public void push(int val) {
            stack.add(val);
            if (minStack.isEmpty() || val <= minStack.get(minStack.size() - 1)) {
                minStack.add(val);
            }
        }

        public void pop() {
            if (stack.isEmpty()) {
                return;
            }
            int removed = stack.remove(stack.size() - 1);
            if (removed == minStack.get(minStack.size() - 1)) {
                minStack.remove(minStack.size() - 1);
            }
        }

        public int top() {
            if (stack.isEmpty()) {
                return 0;
            }
            return stack.get(stack.size() - 1);
        }

        public int getMin() {
            return minStack.get(minStack.size() - 1);
        }
    }

    /**
     * Your MinStack object will be instantiated and called as such:
     * MinStack obj = new MinStack();
     * obj.push(val);
     * obj.pop();
     * int param_3 = obj.top();
     * int param_4 = obj.getMin();
     */

Here is the testcase result –>
getMin() returns -2 instead of -1