diff --git a/Lab20/Lab20.sln b/Lab20/Lab20.sln
new file mode 100644
index 0000000..f98a931
--- /dev/null
+++ b/Lab20/Lab20.sln
@@ -0,0 +1,31 @@
+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 17
+VisualStudioVersion = 17.11.35312.102
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "Lab20", "Lab20\Lab20.vcxproj", "{BB058FAE-9FAC-4094-A7D0-BEB0E36FF1B4}"
+EndProject
+Global
+ GlobalSection(SolutionConfigurationPlatforms) = preSolution
+ Debug|x64 = Debug|x64
+ Debug|x86 = Debug|x86
+ Release|x64 = Release|x64
+ Release|x86 = Release|x86
+ EndGlobalSection
+ GlobalSection(ProjectConfigurationPlatforms) = postSolution
+ {BB058FAE-9FAC-4094-A7D0-BEB0E36FF1B4}.Debug|x64.ActiveCfg = Debug|x64
+ {BB058FAE-9FAC-4094-A7D0-BEB0E36FF1B4}.Debug|x64.Build.0 = Debug|x64
+ {BB058FAE-9FAC-4094-A7D0-BEB0E36FF1B4}.Debug|x86.ActiveCfg = Debug|Win32
+ {BB058FAE-9FAC-4094-A7D0-BEB0E36FF1B4}.Debug|x86.Build.0 = Debug|Win32
+ {BB058FAE-9FAC-4094-A7D0-BEB0E36FF1B4}.Release|x64.ActiveCfg = Release|x64
+ {BB058FAE-9FAC-4094-A7D0-BEB0E36FF1B4}.Release|x64.Build.0 = Release|x64
+ {BB058FAE-9FAC-4094-A7D0-BEB0E36FF1B4}.Release|x86.ActiveCfg = Release|Win32
+ {BB058FAE-9FAC-4094-A7D0-BEB0E36FF1B4}.Release|x86.Build.0 = Release|Win32
+ EndGlobalSection
+ GlobalSection(SolutionProperties) = preSolution
+ HideSolutionNode = FALSE
+ EndGlobalSection
+ GlobalSection(ExtensibilityGlobals) = postSolution
+ SolutionGuid = {EE9CBB1C-290E-4F58-858E-3C60C5EDD527}
+ EndGlobalSection
+EndGlobal
diff --git a/Lab20/Lab20/Lab20.vcxproj b/Lab20/Lab20/Lab20.vcxproj
new file mode 100644
index 0000000..00ce72d
--- /dev/null
+++ b/Lab20/Lab20/Lab20.vcxproj
@@ -0,0 +1,135 @@
+
+
+
+
+ Debug
+ Win32
+
+
+ Release
+ Win32
+
+
+ Debug
+ x64
+
+
+ Release
+ x64
+
+
+
+ 17.0
+ Win32Proj
+ {bb058fae-9fac-4094-a7d0-beb0e36ff1b4}
+ Lab20
+ 10.0
+
+
+
+ Application
+ true
+ v143
+ Unicode
+
+
+ Application
+ false
+ v143
+ true
+ Unicode
+
+
+ Application
+ true
+ v143
+ Unicode
+
+
+ Application
+ false
+ v143
+ true
+ Unicode
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ Level3
+ true
+ WIN32;_DEBUG;_CONSOLE;%(PreprocessorDefinitions)
+ true
+
+
+ Console
+ true
+
+
+
+
+ Level3
+ true
+ true
+ true
+ WIN32;NDEBUG;_CONSOLE;%(PreprocessorDefinitions)
+ true
+
+
+ Console
+ true
+ true
+ true
+
+
+
+
+ Level3
+ true
+ _DEBUG;_CONSOLE;%(PreprocessorDefinitions)
+ true
+
+
+ Console
+ true
+
+
+
+
+ Level3
+ true
+ true
+ true
+ NDEBUG;_CONSOLE;%(PreprocessorDefinitions)
+ true
+
+
+ Console
+ true
+ true
+ true
+
+
+
+
+
+
+
+
+
\ No newline at end of file
diff --git a/Lab20/Lab20/Lab20.vcxproj.filters b/Lab20/Lab20/Lab20.vcxproj.filters
new file mode 100644
index 0000000..e8deb3d
--- /dev/null
+++ b/Lab20/Lab20/Lab20.vcxproj.filters
@@ -0,0 +1,22 @@
+
+
+
+
+ {4FC737F1-C7A5-4376-A066-2A32D752A2FF}
+ cpp;c;cc;cxx;c++;cppm;ixx;def;odl;idl;hpj;bat;asm;asmx
+
+
+ {93995380-89BD-4b04-88EB-625FBE52EBFB}
+ h;hh;hpp;hxx;h++;hm;inl;inc;ipp;xsd
+
+
+ {67DA6AB6-F800-4c08-8B7A-83BB121AAD01}
+ rc;ico;cur;bmp;dlg;rc2;rct;bin;rgs;gif;jpg;jpeg;jpe;resx;tiff;tif;png;wav;mfcribbon-ms
+
+
+
+
+ Исходные файлы
+
+
+
\ No newline at end of file
diff --git a/Lab20/Lab20/main.cpp b/Lab20/Lab20/main.cpp
new file mode 100644
index 0000000..f71251b
--- /dev/null
+++ b/Lab20/Lab20/main.cpp
@@ -0,0 +1,214 @@
+// addToHead, printList, deleteFromHead, contains, clearList.
+#define _CRT_SECURE_NO_WARNINGS
+
+#include
+#include
+#include
+
+struct Node {
+ int data;
+ struct Node* next;
+};
+
+
+struct Node* first = NULL;
+
+
+void printList() {
+ struct Node* ptr = first;
+ while (ptr != NULL) {
+ printf("(%d) -> ", ptr->data);
+ ptr = ptr->next;
+ }
+ printf("NULL\n");
+}
+
+
+void addToHead(int value) {
+ struct Node* newNode = (struct Node*)malloc(sizeof(struct Node));
+
+ newNode->next = first;
+ newNode->data = value;
+
+ first = newNode;
+}
+
+
+int deleteFromHead() {
+ int value = first->data;
+ struct Node* delNode = first;
+ first = first->next;
+ free(delNode);
+ return value;
+}
+
+
+int contains(int value) {
+ struct Node* ptr = first;
+ while (ptr != NULL) {
+ if (ptr->data == value) {
+ return 1;
+ }
+ ptr = ptr->next;
+ }
+ return 0;
+}
+
+
+void clearList() {
+ while (first != NULL)
+ {
+ struct Node* delNode = first;
+ first = first->next;
+ free(delNode);
+ }
+}
+
+
+int sum() {
+ struct Node* ptr = first;
+ int s = 0;
+ while (ptr != NULL) {
+ s += ptr->data;
+ ptr = ptr->next;
+ }
+ return s;
+}
+
+
+int even() {
+ struct Node* ptr = first;
+ int s = 0;
+ int cnt = 0;
+ while (ptr != NULL && s % 2 == 0) {
+ s += ptr->data;
+ ptr = ptr->next;
+ cnt++;
+ }
+ return cnt;
+}
+
+
+void printListX10() {
+ struct Node* ptr = first;
+ int s = 0;
+ while (ptr != NULL) {
+ if (ptr->data % 2 == 1) {
+ printf("(%d) -> ", ptr->data*10);
+ }
+ else {
+ printf("(%d) -> ", ptr->data);
+ }
+ ptr = ptr->next;
+ }
+ printf("NULL\n");
+}
+
+void elementIx100(int i) {
+ struct Node* ptr = first;
+ int s = 0, index = 0;
+ while (ptr != NULL) {
+ if (index == i) {
+ ptr->data = ptr->data * 100;
+ return;
+ }
+ ptr = ptr->next;
+ index++;
+ }
+ printf("NULL\n");
+}
+
+void elementIx10Left(int i) {
+ struct Node* ptr = first;
+ int s = 0, index = 0;
+ while (ptr != NULL) {
+ if (index < i) {
+ ptr->data = ptr->data * 10;
+ }
+ ptr = ptr->next;
+ index++;
+ }
+ printf("NULL\n");
+}
+
+
+void main() {
+ first = NULL;
+ printList();
+
+ addToHead(10);
+ printList();
+
+ addToHead(20);
+ printList();
+
+ addToHead(30);
+ printList();
+
+ printf("sum = %d\n", sum());
+
+ clearList();
+ printList();
+ printf("sum = %d\n", sum());
+ int x, a;
+ scanf("%d", &x);
+ addToHead(x);
+ printList();
+ scanf("%d", &x);
+ addToHead(x);
+ printList();
+ scanf("%d", &x);
+ addToHead(x);
+ printList();
+ scanf("%d", &x);
+ addToHead(x);
+ printList();
+ printf("even = %d\n", even());
+ printf("sum = %d\n", sum());
+ printListX10();
+ printf("Pick num of Element to X 100 - ");
+ scanf_s("%d", &a);
+ printf("\n");
+ elementIx100(a);
+ printList();
+
+ printf("Pick num of Element to X 10 all Left - ");
+ scanf_s("%d", &a);
+ printf("\n");
+ elementIx10Left(a);
+ printList();
+
+ int x1 = deleteFromHead();
+ printf("x1 = %d\n", x1);
+ printList();
+
+ int x2 = deleteFromHead();
+ printf("x2 = %d\n", x2);
+ printList();
+
+
+ clearList();
+ first = NULL;
+ printList();
+
+ addToHead(400);
+ addToHead(300);
+ addToHead(200);
+ addToHead(100);
+ printList();
+
+ printf("contains(100) = %d\n", contains(100));
+ printf("contains(150) = %d\n", contains(150));
+ printf("contains(200) = %d\n", contains(200));
+
+ clearList();
+ printList();
+
+ printf("contains(100) = %d\n", contains(100));
+ printf("contains(150) = %d\n", contains(150));
+ printf("contains(200) = %d\n", contains(200));
+
+
+}
+
+