Design a stack which supports the following operations.
Implement the CustomStack class:
CustomStack(int maxSize) Initializes the object with maxSize which is the maximum number of elements in the stack or do nothing if the stack reached the maxSize.
void push(int x) Adds x to the top of the stack if the stack hasn't reached the maxSize.
int pop() Pops and returns the top of stack or -1 if the stack is empty.
void inc(int k, int val) Increments the bottom k elements of the stack by val. If there are less than k elements in the stack, just increment all the elements in the stack.
Example 1:
Input
["CustomStack","push","push","pop","push","push","push","increment","increment","pop","pop","pop","pop"]
[[3],[1],[2],[],[2],[3],[4],[5,100],[2,100],[],[],[],[]]
Output
[null,null,null,2,null,null,null,null,null,103,202,201,-1]
Explanation
CustomStack customStack = new CustomStack(3); // Stack is Empty []
customStack.push(1);                          // stack becomes [1]
customStack.push(2);                          // stack becomes [1, 2]
customStack.pop();                            // return 2 --> Return top of the stack 2, stack becomes [1]
customStack.push(2);                          // stack becomes [1, 2]
customStack.push(3);                          // stack becomes [1, 2, 3]
customStack.push(4);                          // stack still [1, 2, 3], Don't add another elements as size is 4
customStack.increment(5, 100);                // stack becomes [101, 102, 103]
customStack.increment(2, 100);                // stack becomes [201, 202, 103]
customStack.pop();                            // return 103 --> Return top of the stack 103, stack becomes [201, 202]
customStack.pop();                            // return 202 --> Return top of the stack 102, stack becomes [201]
customStack.pop();                            // return 201 --> Return top of the stack 101, stack becomes []
customStack.pop();                            // return -1 --> Stack is empty return -1.
Constraints:
1 <= maxSize <= 1000
1 <= x <= 1000
1 <= k <= 1000
0 <= val <= 100
At most 1000 calls will be made to each method of increment, push and pop each separately.
class CustomStack:

    
    def __init__(self, maxSize: int):
        self._max_size = maxSize
        self._len = 0
        self._stack = []

    def push(self, x: int) -> None:
        if self._len < self._max_size:
            self._stack.insert(0, x)
            self._len += 1 
            
    def pop(self) -> int:
        if self._len > 0:
            self._len -= 1
            ret = self._stack.pop(0)
        else:
            ret = -1
        return ret

    def increment(self, k: int, val: int) -> None:
        i = 0
        while(i < k and i < self._len):
            self._stack[self._len - i -1] += val
            i += 1


# Your CustomStack object will be instantiated and called as such:
# obj = CustomStack(maxSize)
# obj.push(x)
# param_2 = obj.pop()
# obj.increment(k,val)

class CustomStack:

    
    def __init__(self, maxSize: int):
        self._max_size = maxSize
        self._len = 0
        self._stack = []

    def push(self, x: int) -> None:
        if self._len < self._max_size:
            self._stack.insert(0, x)
            self._len += 1 
            
    def pop(self) -> int:
        if self._len > 0:
            self._len -= 1
            ret = self._stack.pop(0)
        else:
            ret = -1
        return ret

    def increment(self, k: int, val: int) -> None:
        i = 0
        while(i < k and i < self._len):
            self._stack[self._len - i -1] += val
            i += 1


# Your CustomStack object will be instantiated and called as such:
# obj = CustomStack(maxSize)
# obj.push(x)
# param_2 = obj.pop()
# obj.increment(k,val)
