===============================
🏠 SMART HOME AUTOMATION SYSTEM
===============================

import 'dart:io';

void main() {
  const int minTemp = 15;
  const int maxTemp = 30;

  bool lightsOn = false;
  int temperature = 20;
  bool securityArmed = false;

  while (true) {
    print('\n=== SMART HOME SYSTEM ===');
    print('1. Toggle Lights');
    print('2. Set Thermostat Temperature');
    print('3. Arm/Disarm Security System');
    print('4. View System Status');
    print('5. Exit');
    stdout.write('Choose an option: ');
    String? choice = stdin.readLineSync();

    if (choice == '5') {
      print('Exiting Smart Home System... Goodbye!');
      break;
    }

    switch (choice) {
      case '1':
        lightsOn = !lightsOn;
        print('Lights are now ${lightsOn ? "ON" : "OFF"}');
        break;

      case '2':
        stdout.write('Enter temperature ($minTemp-$maxTemp): ');
        int? temp = int.tryParse(stdin.readLineSync() ?? '');
        if (temp != null && temp >= minTemp && temp <= maxTemp) {
          temperature = temp;
          print('Thermostat set to $temperature°C');
        } else {
          print('Invalid temperature! Must be between $minTemp and $maxTemp.');
        }
        break;

      case '3':
        securityArmed = !securityArmed;
        print('Security system is now ${securityArmed ? "ARMED" : "DISARMED"}');
        break;

      case '4':
        String lightsStatus = lightsOn ? "ON" : "OFF";
        String secStatus = securityArmed ? "ARMED" : "DISARMED";

        String dayType = '';
        if (temperature % 3 == 0 && temperature % 5 == 0) {
          dayType = 'Perfect Day';
        } else if (temperature % 3 == 0) {
          dayType = 'Cool Day';
        } else if (temperature % 5 == 0) {
          dayType = 'Warm Day';
        }

        print('\n--- SYSTEM STATUS ---');
        print('Lights: $lightsStatus');
        print('Thermostat: $temperature°C ${dayType.isNotEmpty ? "($dayType)" : ""}');
        print('Security: ${secStatus.toUpperCase()}');
        break;

      default:
        print('Invalid choice. Try again.');
    }
  }
}

===============================
💰 BUDGET MANAGEMENT APPLICATION
===============================

import 'dart:io';

void main() {
  List<Map<String, double>> incomeList = [];
  List<Map<String, double>> expenseList = [];

  print('=== WELCOME TO BUDGET MANAGEMENT SYSTEM ===');

  while (true) {
    print('\n1. Add Income');
    print('2. Add Expense');
    print('3. View Summary');
    print('4. Exit');
    stdout.write('Choose an option: ');
    String? choice = stdin.readLineSync();

    if (choice == '4') {
      print('Exiting Budget Management System... Goodbye!');
      break;
    }

    switch (choice) {
      case '1':
        stdout.write('Enter income description: ');
        String? desc = stdin.readLineSync();
        stdout.write('Enter income amount: ');
        double? amount = double.tryParse(stdin.readLineSync() ?? '');
        if (amount != null && amount >= 0) {
          incomeList.add({desc ?? 'Unnamed Income': amount});
          print('Income added successfully!');
        } else {
          print('Invalid amount!');
        }
        break;

      case '2':
        stdout.write('Enter expense description: ');
        String? desc = stdin.readLineSync();
        stdout.write('Enter expense amount: ');
        double? amount = double.tryParse(stdin.readLineSync() ?? '');
        if (amount != null && amount >= 0) {
          expenseList.add({desc ?? 'Unnamed Expense': amount});
          print('Expense added successfully!');
        } else {
          print('Invalid amount!');
        }
        break;

      case '3':
        double totalIncome = 0;
        double totalExpenses = 0;

        for (var entry in incomeList) {
          totalIncome += entry.values.first;
        }
        for (var entry in expenseList) {
          totalExpenses += entry.values.first;
        }

        double net = totalIncome - totalExpenses;
        print('\n--- BUDGET SUMMARY ---');
        print('Total Income: \$${totalIncome.toStringAsFixed(2)}');
        print('Total Expenses: \$${totalExpenses.toStringAsFixed(2)}');
        if (net >= 0) {
          print('Your net profit is \$${net.toStringAsFixed(2)}');
          double tax = net > 0 ? net * 0.15 : 0;
          print('Tax to pay (15%): \$${tax.toStringAsFixed(2)}');
        } else {
          print('Your net loss is \$${net.abs().toStringAsFixed(2)}');
        }
        break;

      default:
        print('Invalid choice. Try again.');
    }
  }
}