diff --git a/task_01/src/main.cpp b/task_01/src/main.cpp
index 0e4393ba..5b0faafc 100644
--- a/task_01/src/main.cpp
+++ b/task_01/src/main.cpp
@@ -1,3 +1,7 @@
 #include <iostream>
+#include <vector>
 
-int main() { return 0; }
+#include "util.hpp"
+#include "utils.hpp"
+
+int main() { return 0; }
\ No newline at end of file
diff --git a/task_01/src/test.cpp b/task_01/src/test.cpp
index ef5a86ae..3cee3f68 100644
--- a/task_01/src/test.cpp
+++ b/task_01/src/test.cpp
@@ -1,8 +1,21 @@
 
 #include <gtest/gtest.h>
 
-#include "topology_sort.hpp"
+#include <stdexcept>
+#include <vector>
 
-TEST(TopologySort, Simple) {
-  ASSERT_EQ(1, 1);  // Stack []
+#include "utils.hpp"
+TEST(utils, Simple) {
+  ASSERT_EQ(FindSummands(std::vector<int>{1, 2, 3, 4, 5, 7, 8, 12}, 7),
+            (std::pair<int, int>{2, 5}));
+  ASSERT_EQ(FindSummands(std::vector<int>{1, 2, 3, 4, 5, 7, 8, 12}, 13),
+            (std::pair<int, int>{1, 12}));
+  EXPECT_THROW(FindSummands(std::vector<int>{1, 2, 3, 4, 5, 7, 8, 12}, 21),
+               NoAnswer);
+  EXPECT_THROW(FindSummands(std::vector<int>{1, 2, 3, 4, 5, 7, 8, 12}, -1),
+               NoAnswer);
+  EXPECT_THROW(FindSummands(std::vector<int>{1, 1, 1, 1}, 3), NoAnswer);
+  ASSERT_EQ(FindSummands(std::vector<int>{1, 1, 1, 1}, 2),
+            (std::pair<int, int>{1, 1}));
+  EXPECT_THROW(FindSummands(std::vector<int>{}, 0), NoAnswer);
 }
diff --git a/task_01/src/topology_sort.cpp b/task_01/src/topology_sort.cpp
deleted file mode 100644
index e53f670c..00000000
--- a/task_01/src/topology_sort.cpp
+++ /dev/null
@@ -1 +0,0 @@
-#include "topology_sort.hpp"
diff --git a/task_01/src/topology_sort.hpp b/task_01/src/topology_sort.hpp
deleted file mode 100644
index 6f70f09b..00000000
--- a/task_01/src/topology_sort.hpp
+++ /dev/null
@@ -1 +0,0 @@
-#pragma once
diff --git a/task_01/src/utils.cpp b/task_01/src/utils.cpp
new file mode 100644
index 00000000..7a8ff8f0
--- /dev/null
+++ b/task_01/src/utils.cpp
@@ -0,0 +1,23 @@
+#include "utils.hpp"
+
+#include <cstddef>
+#include <iostream>
+#include <stdexcept>
+#include <utility>
+#include <vector>
+
+std::pair<int, int> FindSummands(const std::vector<int> array, int number) {
+  int first_index = 0;
+  int second_index = array.size() - 1;
+
+  while (first_index < second_index) {
+    int first_summand = array[first_index];
+    int second_summand = array[second_index];
+    int sum = first_summand + second_summand;
+    if (sum == number)
+      return std::pair<int, int>{first_summand, second_summand};
+    if (sum < number) first_index++;
+    if (sum > number) second_index--;
+  }
+  throw NoAnswer("Unable to find the right elements");
+}
diff --git a/task_01/src/utils.hpp b/task_01/src/utils.hpp
new file mode 100644
index 00000000..d760cf67
--- /dev/null
+++ b/task_01/src/utils.hpp
@@ -0,0 +1,11 @@
+#pragma once
+#include <stdexcept>
+#include <utility>
+#include <vector>
+
+class NoAnswer : public std::runtime_error {
+ public:
+  using std::runtime_error::runtime_error;
+};
+
+std::pair<int, int> FindSummands(const std::vector<int> array, int number);
\ No newline at end of file