module stack_model {
  // Define the maximum capacity of the stack
  const n : int;
  axiom n > 0; // Ensure n is positive

  // Abstract representation of the stack
  type stack_t;

  // State variables
  var s : stack_t;
  var size : int;

  // Initialization
  init {
    size = 0;
  }

  // Abstract operations
  procedure push() modifies s, size {
    if (size < n) {
      // Abstract representation of pushing an element onto the stack
      // Assuming an abstract operation 'abstract_push' that modifies 's'
      call abstract_push(s);
      size = size + 1;
    }
  }

  procedure pop() modifies s, size {
    if (size > 0) {
      // Abstract representation of popping the top element from the stack
      // Assuming an abstract operation 'abstract_pop' that modifies 's'
      call abstract_pop(s);
      size = size - 1;
    }
  }

  function top(s : stack_t) : int {
    // Abstract representation of retrieving the top element
    // Assuming an abstract function 'abstract_top' that does not modify 's'
    return abstract_top(s);
  }

  // Invariants
  invariant size_non_negative : size >= 0;
  invariant size_within_capacity : size <= n;
}
