/* The stack pointer always points to the first free position on the stack. This is the common way to implement  the stack. */

int stack [30];
int stackPointer = 0;

void push(int element) {
  stack[stackPointer] = element;
  stackPointer++;
}

bool isEmpty() {
  return stackPointer == 0;
}

int pop() {
  if (!isEmpty()) {
    stackPointer--;
    return stack[stackPointer];
  } 
}