71_Implement_Two_Stacks_in_One_Array

class TwoStacks:
    arr=[-1]
    def __init__(self):
        self.arr=[-1]
    # Function to push an integer into stack 1
    def push1(self, x):
        self.arr.append(x)

    # Function to push an integer into stack 2
    def push2(self, x):
        self.arr=[x]+self.arr

    # Function to remove an element from top of stack 1
    def pop1(self):
        if self.arr[-1]!=-1:
            x=self.arr[-1]
            self.arr=self.arr[:-1]
            return x
        return -1

    # Function to remove an element from top of stack 2
    def pop2(self):
        if self.arr[0]!=-1:
            x=self.arr[0]
            self.arr=self.arr[1:]
            return x
        return -1