diff --git a/2sem/programming basics/18/100.cpp b/2sem/programming basics/18/100.cpp
new file mode 100644
index 0000000..30a8116
--- /dev/null
+++ b/2sem/programming basics/18/100.cpp	
@@ -0,0 +1,208 @@
+// pb_18_100.cpp
+// Горбацевич Андрей
+#include <iostream>
+#include <fstream>
+#include <ctime>
+
+#ifdef NDEVENV
+#define dfunc(func) {func;}
+#else
+#define dfunc(func)
+#endif
+
+struct Node {
+    int data;
+    Node *next = nullptr;
+    Node *prev = nullptr;
+
+    explicit Node(int d) : data(d) {};
+
+    ~Node() {
+        delete next;
+        next = nullptr;
+        prev = nullptr;
+    }
+};
+
+struct BiLinkedList {
+    int len = 0;
+    Node *first = nullptr;
+    Node *last = nullptr;
+
+    ~BiLinkedList() {
+        delete first;
+        first = nullptr;
+        last = nullptr;
+    }
+
+    void push_node(Node *n) {
+        if (this->last == this->first) {
+            if (this->last == nullptr) {
+                this->first = this->last = n;
+            }
+            else {
+                this->first->next = n;
+                n->prev = this->first;
+                this->last = n;
+            }
+        }
+        else {
+            n->prev = this->last;
+            this->last->next = n;
+            this->last = n;
+        }
+
+        this->len += 1;
+    }
+
+    void prepend_node(Node *n, Node *before) {
+        if (before == nullptr) {
+            this->push_node(n);
+        }
+        else if (before == this->first) {
+            n->next = this->first;
+            this->first = n;
+        }
+        else {
+            n->next = before;
+            n->prev = before->prev;
+            n->prev->next = n;
+            n->next->prev = n;
+        }
+
+        this->len += 1;
+    }
+
+    void remove_at(int pos) {
+        if (pos > this->len || pos < 0 || this->len <= 0) {
+            return;
+        }
+        Node *cn = nullptr;
+        if (this->len == 1) {
+            this->first->next = nullptr;
+            delete this->first;
+        }
+        else if (pos == 0) {
+            cn = this->first;
+            cn->next->prev = nullptr;
+            this->first = cn->next;
+        }
+        else if (pos == this->len - 1) {
+            cn = this->last;
+            cn->prev->next = nullptr;
+            this->last = cn->prev;
+        }
+        else if (pos > this->len/2) {
+            int cpos = len - 1;
+            cn = this->last;
+            while (cpos != pos) {
+                cn = cn->prev;
+                cpos -= 1;
+            }
+            cn->prev->next = cn->next;
+            cn->prev = cn->prev;
+        }
+        else {
+            int cpos = 0;
+            cn = this->first;
+            while (cpos != pos) {
+                cn = cn->next;
+                cpos += 1;
+            }
+            cn->prev->next = cn->next;
+            cn->prev = cn->prev;
+        }
+
+        if (cn != nullptr) {
+            cn->next = cn->prev = nullptr;
+            delete cn;
+        }
+
+        this->len -= 1;
+        if (this->len == 0) {
+            this->first = this->last = nullptr;
+        }
+    }
+
+    void print_list(std::ostream &ost) {
+        auto cn = this->first;
+        while (cn != nullptr) {
+            ost << cn->data << " ";
+            cn = cn->next;
+        }
+    }
+
+    void print_list_rev(std::ostream &ost) {
+        auto cn = this->last;
+        while (cn != nullptr) {
+            ost << cn->data << " ";
+            cn = cn->prev;
+        }
+    }
+};
+
+int main() {
+    srand(time(nullptr)+0);
+    std::string path_in = "in.txt"; // путь до входного файла
+
+    BiLinkedList list;
+
+    std::ifstream ifs(path_in);
+    if (!ifs.is_open())
+    {
+        std::cerr << "Unable to open file" << std::endl;
+        return 1;
+    }
+
+    // possible input: 12 11 19 91 91 120 19 19 11 19 12 300
+    { // водим данные в список
+        while (!ifs.eof() && !ifs.fail()) {
+            int i;
+            ifs >> i;
+            list.push_node(new Node(i));
+        }
+    }
+
+    dfunc(printf("Size: %d; [", list.len));
+    dfunc(list.print_list(std::cout));
+    dfunc(printf("]\n"));
+
+    // possible output: 12 6 6 11 12 1 11 19 91 91 120 7 53 5 95
+    //                  122 19 19 11 19 12 1 9 5 4 12 300 219 139 269 165 87
+    { // выполняем задание
+        auto cn = list.first;
+        while (cn != nullptr) {
+            if (cn->data % std::to_string(cn->data).length() == 0) {
+                list.prepend_node(new Node(rand() % (cn->data + 3)), cn->next);
+                list.prepend_node(new Node(rand() % (cn->data + 3)), cn->next);
+                list.prepend_node(new Node(rand() % (cn->data + 3)), cn->next);
+                list.prepend_node(new Node(rand() % (cn->data + 3)), cn->next);
+                list.prepend_node(new Node(rand() % (cn->data + 3)), cn->next);
+                cn = cn->next->next->next->next->next;
+            }
+            cn = cn->next;
+        }
+    }
+
+    for (;;) {
+        printf("Size: %d; [", list.len);
+        list.print_list(std::cout);
+        printf("]\n");
+
+        printf("Delete element at (`-1` - to exit) >>>");
+        int pos;
+        scanf("%d", &pos);
+        if (pos == -1) {
+            break;
+        }
+        list.remove_at(pos);
+    }
+
+    printf("Straight order: ");
+    list.print_list(std::cout);
+    printf("\nReversed order: ");
+    list.print_list_rev(std::cout);
+    printf("\n");
+
+    return 0;
+}
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