Implement two stacks in an array

// Implement two stacks in an array - easy - 07/08/2023


class twoStacks
{
    int arr[];
    int size;
    int top1, top2;
    twoStacks()
    {
        size = 100; 
        arr = new int[100]; 
        top1 = -1; 
        top2 = size;
    }
    //Function to push an integer into the stack1.
    void push1(int x)
    {
         if (top1 < top2 - 1) {
            top1++;
            arr[top1] = x;
        }
        else {
            return;
        }
    }
    //Function to push an integer into the stack2.
    void push2(int x)
    {
       if (top1 < top2 - 1) {
            top2--;
            arr[top2] = x;
        }
        else {
            return ;
        }
    }
    //Function to remove an element from top of the stack1.
    int pop1()
    {
        if (top1 >= 0) {
            int x = arr[top1];
            top1--;
            return x;
        }
        else {
            return -1;
        }
    }
    //Function to remove an element from top of the stack2.
    int pop2()
    {
        if (top2 < size) {
            int x = arr[top2];
            top2++;
            return x;
        }
        else {
            return -1;
        }
    }
}