@@ -1,24 +1,44 @@
 import java.util.Arrays;
+import java.util.HashMap;
+import java.util.Map;
 
 public class Exercise8_5 {
-	
-	public static void sieve(int n) {
-		int[] start = new int[n];
-		boolean[] bool = new boolean[n];
-		for (int i = 0; i < start.length; i++) {
-			start[i] = i;
-		}
-		for (int i = 0; i < bool.length; i++) {
-			if (start[i] == i * i) {
-				bool[i] = false;
-			} else {
+		
+		public static  void sieve(int limit) {
+			
+			int[] nums = new int[limit];
+			for (int i = 0; i < nums.length; i++) {
+				nums[i] = i;
+			}
+			System.out.println(Arrays.toString(nums));
+			
+			boolean[] bool = new boolean[limit];
+			for (int i = 2; i < bool.length; i++) {
 				bool[i] = true;
 			}
-		}
+			
+			// Mark all composite numbers
+			for (int i = 2; i < (bool.length / 2); i++) {
+				if (bool[i]) {
+//					bool[i] = false;
+					int multiple = 2;
+					while (i * multiple < bool.length) {
+						bool [i * multiple] = false;
+						multiple++;
+					}
+				}
+			}
 
-		System.out.println(Arrays.toString(start));
-		System.out.println(Arrays.toString(bool));
-	}
+			
+			Map myMap = new HashMap(bool.length);
+			for (int i = 0; i < nums.length; i++) {
+				myMap.put(nums[i], bool[i]);
+			}
+			
+			
+			System.out.println(Arrays.toString(bool));
+			System.out.println(myMap);
+		}
 
 	public static void main(String[] args) {
 		sieve(120);
 
@@ -0,0 +1,37 @@
+import java.util.Arrays;
+import java.util.Random;
+
+/**
+ * Example code related to histograms.
+ */
+public class Histogram2 {
+
+    /**
+     * Returns an array of random integers.
+     */
+    public static int[] randomArray(int size) {
+        Random random = new Random();
+        int[] a = new int[size];
+        for (int i = 0; i < a.length; i++) {
+            a[i] = random.nextInt(100);
+        }
+        return a;
+    }
+
+    public static void main(String[] args) {
+
+        int[] scores = randomArray(100);
+
+        // making a histogram
+        int[] counts = new int[100];
+        for (int i = 0; i < scores.length; i++) {
+            int index = scores[i];
+            counts[index]++;
+        }
+        
+        System.out.println(Arrays.toString(scores));
+        System.out.println(Arrays.toString(counts));
+
+    }
+
+}
@@ -0,0 +1,19 @@
+
+public class Exercise9_1 {
+	public static void main(String[] args) {
+		boolean myB1 = false;
+		char myChar1 = 'm';
+		int myInt1 = 1;
+		double myD1 = 1.0;
+		String myString1 = "MyString1";
+		
+		boolean myB2 = true;
+		char myChar2 = 'n';
+		int myInt2 = 2;
+		double myD2 = 2.0;
+		String myString2 = "MyString2";
+		
+		System.out.println(myD2 + myInt1);
+		System.out.println((myString1 + myD2).getClass().getName());
+	}
+}
@@ -0,0 +1,41 @@
+import java.util.Arrays;
+
+public class Exercise9_2 {
+
+	public static void letterHist(String lettersCount) {
+
+		String temp = lettersCount.toLowerCase();
+
+		char[] myCharsFromString = temp.toCharArray();
+
+		// creating alfabet array
+		char[] alfabet = new char[25];
+		char c = 'a';
+		for (int i = 0; i < alfabet.length; i++) {
+			alfabet[i] = c;
+			c++;
+		}
+
+		// making a histogram
+		int[] counts = new int[25];
+
+		for (int i = 0; i < myCharsFromString.length; i++) {
+			char index = myCharsFromString[i];
+			for (int j = 0; j < alfabet.length; j++) {
+				if (alfabet[j] == index) {
+					counts[j]++;
+				}
+			}
+
+		}
+
+		System.out.println(Arrays.toString(alfabet));
+		System.out.println(Arrays.toString(counts));
+
+	}
+
+	public static void main(String[] args) {
+		letterHist("My test");
+
+	}
+}
@@ -0,0 +1,25 @@
+
+public class MyMath {
+	
+	// Nai maluk obsht delitel
+	public static int nod(int a, int b) {
+		while (b != 0) {
+			int t = b;
+			b = a % b;
+			a = t;
+		}
+		return a;
+	}
+	
+	// Nai malko obshto kratno
+	public static int nok(int a, int b) {
+			int nod = nod(a, b);
+			int result = a * b;
+		return result / nod;
+	}
+
+	public static void main(String[] args) {
+		System.out.println(nod(1071, 462));
+		System.out.println(nok(1071, 462));
+	}
+}