diff --git a/homeworks/19_Lachezar_Velinov/01_checkCircles.py b/homeworks/18_Lachezar_Velinov/01_checkCircles.py
similarity index 100%
rename from homeworks/19_Lachezar_Velinov/01_checkCircles.py
rename to homeworks/18_Lachezar_Velinov/01_checkCircles.py
diff --git a/homeworks/18_Lachezar_Velinov/02_task1.py b/homeworks/18_Lachezar_Velinov/02_task1.py
new file mode 100644
index 0000000..de530ee
--- /dev/null
+++ b/homeworks/18_Lachezar_Velinov/02_task1.py
@@ -0,0 +1,51 @@
+
+
+def getSectorValues(matrix, rowpos, columnpos, sectorList): #finds all the values of a sector and returns them
+    sectorList.append(matrix[rowpos][columnpos]) 
+    matrix[rowpos][columnpos] = 0 #turns an appended square into a black square
+    for i in range(-1, 2):
+        for j in range(-1, 2):
+            if rowpos + i >= 0 and columnpos + j >= 0 and rowpos + i < len(matrix) and columnpos + j < len(matrix[i]): #check if location is in range of the matrix
+                if matrix[rowpos+i][columnpos+j] != 0: #check if square is non black
+                    getSectorValues(matrix, rowpos+i, columnpos+j, sectorList) #reccursive calling
+    return
+
+
+def findSector(matrix): #looks for a sector and returns it's average value
+    returnValueList = [] #holds average value of every sector
+    sectorList = [] #holds all the values of a single sector
+    for rowpos, row in enumerate(matrix): 
+        for columnpos, column in enumerate(row): #go throught the matrix to find a non black square
+            if matrix[rowpos][columnpos] > 0:
+                getSectorValues(matrix, rowpos, columnpos, sectorList)
+                average = 0 #average value of a sector
+                for amount in sectorList:
+                    average+=amount
+                average /= len(sectorList)
+                del sectorList[:] #reset the sector list
+                returnValueList.append(average) #add average sector value to rest list
+
+    return returnValueList
+
+
+def avg_brightnes(matrix):    
+    outputList = [] 
+    outPutList = findSector(matrixCopy)
+    outPutList.sort(reverse=True) #sort list in descending order
+    for i in outPutList: #prints final values
+        print (i)
+
+
+
+
+matrix = ( #test matrix
+    (170,   0,   0, 255, 221,   0),
+    ( 68,   0,  17,   0,   0,  68),
+    (221,   0, 238, 136,   0, 255),
+    (  0,   0,  85,   0, 136, 238),
+    (238,  17,   0,  68,   0, 255),
+    ( 85, 170,   0, 221,  17,   0)
+)
+
+matrixCopy = [list(matrix_inner) for matrix_inner in matrix] #since we cannot use the original matrix, we make a copy
+avg_brightnes(matrixCopy)
diff --git a/homeworks/18_Lachezar_Velinov/02_task2.py b/homeworks/18_Lachezar_Velinov/02_task2.py
new file mode 100644
index 0000000..bc4afe0
--- /dev/null
+++ b/homeworks/18_Lachezar_Velinov/02_task2.py
@@ -0,0 +1,11 @@
+from functools import lru_cache
+
+
+@lru_cache(maxsize=10) #allows us to use 10 most recent values by caching them
+def num_ways(n):
+    if n <= 1:
+        return n
+    return num_ways(n-1) + num_ways(n-2)
+
+
+print(num_ways(23))
diff --git a/homeworks/18_Lachezar_Velinov/02_task3.py b/homeworks/18_Lachezar_Velinov/02_task3.py
new file mode 100644
index 0000000..5dc174e
--- /dev/null
+++ b/homeworks/18_Lachezar_Velinov/02_task3.py
@@ -0,0 +1,16 @@
+def replace(List, Find, Replace):
+    listCopy = list(List)
+
+    for i, value in enumerate(listCopy): #go through list
+        if value == Find:
+            listCopy[i] = Replace #looks for value and replaces it
+
+        elif type(value) in [list, tuple]:
+            listCopy[i] = replace(listCopy[i], Find, Replace) #if container is found, goes inside it
+
+    return listCopy
+
+
+exampleList = [ 'a', 1, [ ['a', 'b'], 1], ([1, 3, 'a'], 'b')]
+res = replace(exampleList, 'a', 'c')
+print(res)