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diff --git a/challenge-138/java/WorkDays.java b/challenge-138/java/WorkDays.java
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+// The Weekly Challenge - 138
+// Task 1 Work Days
+// Usage: java WorkDays YYYY
+
+import java.time.LocalDate;
+
+public class WorkDays
+{
+    public static void main(String[] args)
+    {
+        int year = Integer.parseInt(args[0]);
+        System.out.println(numOfWorkDays(year));
+
+        testing();
+        benchmark();
+
+    }
+
+    public static void testing()
+    {
+        for (int i = 1900; i <= 2400; i++)
+        {
+            if (numOfWorkDays(i) != simple_days_count(i))
+                System.out.println("big event in " + i);
+        }
+    }
+
+    public static int numOfWorkDays (int year) {
+        LocalDate MondayJan = LocalDate.of(year, 1, 1);
+        int ans = 0;
+        int ga = gd(MondayJan);
+        while (ga != 1) 
+        {
+            if (ga <= 5 && ga >= 2) 
+                ans++;
+            MondayJan = MondayJan.plusDays(1);
+            ga = gd(MondayJan);
+        }
+        LocalDate lastDay = MondayJan.plusWeeks(51);
+        ans += 51*5;
+        int gb = gd(lastDay);
+        while (lastDay.getDayOfYear() < lastDay.lengthOfYear()) 
+        {
+            if (gb <= 5 && gb >= 1)
+                ans++;
+            lastDay = lastDay.plusDays(1);
+            gb = gd(lastDay);
+        }
+        ans += gb <= 5 ? 1 : 0;
+        return ans;
+    }
+
+
+    public static int simple_days_count(int year)
+    {
+        int i = 0;
+        LocalDate my_day = LocalDate.of(year, 1, 1);
+        while (my_day.getYear() == year)
+        {
+            if (gd(my_day) != 6 && gd(my_day) != 7)
+            {
+                i++;
+            }
+            my_day = my_day.plusDays(1);
+        }
+        return i;
+    }
+
+
+    public static int gd(LocalDate date)
+    {
+        var a = date.getDayOfWeek();
+        switch(a)
+        {
+            case MONDAY: return 1;
+            case TUESDAY: return 2;
+            case WEDNESDAY: return 3;
+            case THURSDAY: return 4;
+            case FRIDAY: return 5;
+            case SATURDAY: return 6;
+            case SUNDAY: return 7;
+        }
+        return 0;
+    }
+
+    public static void benchmark()
+    {
+        long time_0 = System.nanoTime();
+        for (int i = 1975; i < 2400; i++) {
+            simple_days_count(i);
+        }
+        long time_1 = System.nanoTime();
+        for (int i = 1975; i < 2400; i++) {
+            numOfWorkDays(i);
+        }
+        long time_2 = System.nanoTime();
+        System.out.println("simple_days_count " + (time_1 - time_0));
+        System.out.println("numOfWorkDays " + (time_2 - time_1));
+
+        // Output:
+        // simple_days_count  10398009
+        // numOfWorkDays        344198
+
+    }
+
+}