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..d5bdabb3 100644
--- a/task_01/src/test.cpp
+++ b/task_01/src/test.cpp
@@ -1,8 +1,26 @@
-
 #include <gtest/gtest.h>
 
-#include "topology_sort.hpp"
+#include <stdexcept>
+#include <vector>
+
+#include "utils.hpp"
 
-TEST(TopologySort, Simple) {
-  ASSERT_EQ(1, 1);  // Stack []
+TEST(utils, Simple) {
+  ASSERT_EQ(SumOfElements(9, std::vector<int>{1, 2, 4, 5, 6, 8, 10, 12}),
+            (std::pair<int, int>{1, 8}));
+  ASSERT_EQ(SumOfElements(39, std::vector<int>{1, 2, 4, 5, 6, 9, 10, 35}),
+            (std::pair<int, int>{4, 35}));
+  ASSERT_EQ(SumOfElements(14, std::vector<int>{1, 2, 4, 5, 6, 8, 10, 12}),
+            (std::pair<int, int>{2, 12}));
+  EXPECT_THROW(SumOfElements(187, std::vector<int>{1, 2, 4, 6, 8, 10, 12, 15}),
+               std::logic_error);
+  EXPECT_THROW(SumOfElements(12, std::vector<int>{0, 1, 1, 2, 2}),
+               std::logic_error);
+  ASSERT_EQ(
+      SumOfElements(1338, std::vector<int>{10, 20, 40, 50, 60, 87, 100, 1278}),
+      (std::pair<int, int>{60, 1278}));
+  ASSERT_EQ(SumOfElements(22, std::vector<int>{10, 10, 11, 11, 12, 15}),
+            (std::pair<int, int>{10, 12}));
+  EXPECT_THROW(SumOfElements(22, std::vector<int>{11}), WrongVector);
+  EXPECT_THROW(SumOfElements(1233, std::vector<int>{}), WrongVector);
 }
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..2f1f57c6
--- /dev/null
+++ b/task_01/src/utils.cpp
@@ -0,0 +1,22 @@
+#include "utils.hpp"
+
+#include <iostream>
+#include <utility>
+#include <vector>
+
+std::pair<int, int> SumOfElements(int num, const std::vector<int> arr) {
+  if (arr.size() < 2) {
+    throw WrongVector("Vector is too small");
+  }
+  for (int i = 0, j = arr.size() - 1; i < j;) {
+    auto sum = arr[i] + arr[j];
+    if (sum < num)
+      ++i;
+    else if (sum > num)
+      --j;
+    else if (sum == num) {
+      return std::pair<int, int>{arr[i], arr[j]};
+    }
+  }
+  throw std::logic_error("There is no sum of elements equal to number");
+}
\ No newline at end of file
diff --git a/task_01/src/utils.hpp b/task_01/src/utils.hpp
new file mode 100644
index 00000000..eebc80c8
--- /dev/null
+++ b/task_01/src/utils.hpp
@@ -0,0 +1,9 @@
+#pragma once
+#include <iostream>
+#include <vector>
+
+class WrongVector : public std::runtime_error {
+  using std::runtime_error::runtime_error;
+};
+
+std::pair<int, int> SumOfElements(int num, const std::vector<int> arr);