Modify main() to Fig. 21. Remove DS1 flashing behavior.

To modify `main()` according to Figure 21 and remove the DS1 flashing behavior, follow these steps:

1. **Open the `main.c` file** in your project.
2. **Locate the `main()` function**.
3. **Replace the existing `main()` function** with the content from Figure 21.

Here is the modified `main()` function based on Figure 21:

int main(void)
{
    // Initialize the system
    SystemInit();

    // Initialize the LEDs
    EIE3810_LED_Init();

    // Initialize the Key_Up button for EXTI0
    EIE3810_KeyUp_EXTIInit();

    // Enable the global interrupt
    __enable_irq();

    // Main loop
    while (1)
    {
        // Your main loop code here
    }
}

### Explanation:
- **System Initialization**: `SystemInit();` initializes the system clock and other hardware configurations.
- **LED Initialization**: `EIE3810_LED_Init();` initializes the LEDs.
- **Key_Up Button Initialization**: `EIE3810_KeyUp_EXTIInit();` sets up the Key_Up button to trigger an interrupt on EXTI0.
- **Global Interrupt Enable**: `__enable_irq();` enables global interrupts, allowing the CPU to respond to interrupt requests.
- **Main Loop**: The `while (1)` loop is the main loop where you can place any additional code that needs to run continuously.

By removing the DS1 flashing behavior, you ensure that the LED DS1 will only be controlled by the interrupt handler for Key_Up. Make sure to implement the `EIE3810_KeyUp_EXTIInit()` function and the corresponding interrupt handler `EXTI0_IRQHandler()` as required for the experiment.