diff --git a/sem2/DrozdovaAA/mini_homework_3/input.txt b/sem2/DrozdovaAA/mini_homework_3/input.txt
new file mode 100644
index 00000000..3f95ed8e
--- /dev/null
+++ b/sem2/DrozdovaAA/mini_homework_3/input.txt
@@ -0,0 +1,6 @@
+Hello world
+C++ programming is fun
+Lambda expressions
+STL algorithms
+Short
+A very long string just for testing purposes
\ No newline at end of file
diff --git a/sem2/DrozdovaAA/mini_homework_3/output.txt b/sem2/DrozdovaAA/mini_homework_3/output.txt
new file mode 100644
index 00000000..d1ba4f78
--- /dev/null
+++ b/sem2/DrozdovaAA/mini_homework_3/output.txt
@@ -0,0 +1,32 @@
+original vector:
+Hello world
+C++ programming is fun
+Lambda expressions
+STL algorithms
+Short
+A very long string just for testing purposes
+
+ vector after removing short lines:
+Hello world
+C++ programming is fun
+Lambda expressions
+STL algorithms
+Short
+A very long string just for testing purposes
+
+ vector after replacing spaces with '_': 
+Hello_world
+C++_programming_is_fun
+Lambda_expressions
+STL_algorithms
+Short
+A_very_long_string_just_for_testing_purposes
+
+ search result for word 'Hello' 
+Hello_world
+
+ total characters without '_': 
+101
+
+ vector of string lengths: 
+11 22 18 14 5 44 
diff --git a/sem2/DrozdovaAA/mini_homework_3/sem2_mini_hw_3.cpp b/sem2/DrozdovaAA/mini_homework_3/sem2_mini_hw_3.cpp
new file mode 100644
index 00000000..43795109
--- /dev/null
+++ b/sem2/DrozdovaAA/mini_homework_3/sem2_mini_hw_3.cpp
@@ -0,0 +1,114 @@
+#include <algorithm>
+#include <fstream>
+#include <iostream>
+#include <string>
+#include <vector>
+
+void printStringVector(const std::vector<std::string>& vec,
+                       std::ofstream& out) {
+  for (const auto& str : vec) {
+    out << str << "\n";
+  }
+}
+
+void runProgram() {
+  std::ifstream file_contents("input.txt");
+  std::vector<std::string> original_lines;
+  std::string current_line;
+
+  while (std::getline(file_contents,
+                      current_line)) {  // считываем в вектор с текущей строкой
+    original_lines.push_back(current_line);
+  }
+  file_contents.close();
+
+  // получаем данные от пользователя
+  int length_threshold = 0;
+  std::cout << "length threshold: ";
+  std::cin >> length_threshold;
+
+  std::string search_word;
+  std::cout << "search word: ";
+  std::cin >> search_word;
+
+  std::ofstream out_file("output.txt");
+  if (!out_file.is_open()) {
+    std::cerr << "recording error\n";
+    return;
+  }
+
+  out_file << "original vector:\n";
+  printStringVector(original_lines, out_file);
+
+  // 1 - удаление всех строк меньше заданного значения
+  std::vector<std::string> filtered_lines = original_lines;  // копия строк
+  filtered_lines.erase(
+      std::remove_if(filtered_lines.begin(), filtered_lines.end(),
+                     [length_threshold](const std::string& str) {
+                       return str.length() <
+                              static_cast<size_t>(length_threshold);
+                     }),
+      filtered_lines.end());
+
+  out_file << "\n vector after removing short lines:\n";
+  printStringVector(filtered_lines, out_file);
+
+  // 2 - замена пробелов на _
+  std::vector<std::string> underscored_lines =
+      filtered_lines;  // копия отфитрованного
+  std::for_each(
+      underscored_lines.begin(), underscored_lines.end(),
+      [](std::string& str) { std::replace(str.begin(), str.end(), ' ', '_'); });
+
+  out_file << "\n vector after replacing spaces with '_': \n";
+  printStringVector(underscored_lines, out_file);
+
+  // 3 - поиск строки, содержащей слово пользователя
+  auto find_it =
+      std::find_if(filtered_lines.begin(), filtered_lines.end(),
+                   [&search_word](const std::string& str) {
+                     return str.find(search_word) != std::string::npos;
+                   });
+
+  out_file << "\n search result for word '" << search_word << "' \n";
+  if (find_it != filtered_lines.end()) {
+    // индекс найденной строки
+    auto index = std::distance(filtered_lines.begin(), find_it);
+    out_file << underscored_lines[index] << "\n";
+  } else {
+    out_file << "word not found\n";
+  }
+
+  // 4 - общее кол-во символов без учёта _
+  size_t total_chars = 0;
+  std::for_each(underscored_lines.begin(), underscored_lines.end(),
+                [&total_chars](const std::string& str) {
+                  total_chars += std::count_if(str.begin(), str.end(),
+                                               [](char c) { return c != '_'; });
+                });
+
+  out_file << "\n total characters without '_': \n";
+  out_file << total_chars << "\n";
+
+  // 5 - вектор чисел с длинами строк
+  std::vector<int> string_lengths;
+  string_lengths.reserve(underscored_lines.size());
+  std::transform(
+      underscored_lines.begin(), underscored_lines.end(),
+      std::back_inserter(string_lengths),
+      [](const std::string& str) { return static_cast<int>(str.length()); });
+
+  out_file << "\n vector of string lengths: \n";
+  for (int len : string_lengths) {
+    out_file << len << " ";
+  }
+  out_file << "\n";
+
+  out_file.close();
+  std::cout << "program completed" << std::endl;
+}
+
+int main() {
+  runProgram();
+  return 0;
+}