public class Multiplication {
    public static Integer multiply(Integer a, Integer b) {
        return a * b;
    }
    
    public static void main() {
        Integer result = multiply(5, 10);
        System.debug('Result: ' + result); // Output: 50
    }
}

public class MyClass {
    public Integer publicVar = 10;     // Accessible everywhere
    private Integer privateVar = 20; // Only within class
    protected Integer protectedVar = 30; // Class + Subclasses
    
    public Integer getValue() {
        return privateVar; // private accessed inside class
    }
}

// Primitive Types
Boolean isActive = true;
Integer count = 10;
String name = 'Saurabh Samir';
Double price = 99.99;
Date today = Date.today();

// Non-Primitive Types
List names = new List{'A', 'B', 'C'};
Map scores = new Map{'Saurabh' => 95};
Account acc = new Account(Name = 'Test');

Integer a = 10, b = 3;

// Arithmetic
Integer sum = a + b;      // 13
Integer mod = a % b;       // 1

// Comparison
Boolean isEqual = (a == b); // false
Boolean isGreater = (a > b); // true

// Logical
Boolean result = (a > 5 && b < 5); // true

// Ternary
String status = (a > b) ? 'A is greater' : 'B is greater';

public class Counter {
    // Static variable — shared across all instances
    public static Integer staticCount = 0;
    
    // Instance variable — separate per object
    public Integer instanceCount = 0;
    
    public static void incrementStatic() {
        staticCount++; // All instances share this
    }
    
    public void incrementInstance() {
        instanceCount++; // Only this object changes
    }
}

// Usage
Counter c1 = new Counter();
Counter c2 = new Counter();
Counter.incrementStatic();  // staticCount = 1 (shared)
c1.incrementInstance();  // c1.instanceCount = 1 (separate)
c2.incrementInstance();  // c2.instanceCount = 1 (separate)