diff --git a/main.ipynb b/main.ipynb
new file mode 100644
index 0000000..0a91670
--- /dev/null
+++ b/main.ipynb
@@ -0,0 +1,68 @@
+{
+ "cells": [
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "32e3594e",
+   "metadata": {},
+   "outputs": [
+    {
+     "ename": "IndexError",
+     "evalue": "list index out of range",
+     "output_type": "error",
+     "traceback": [
+      "\u001b[31m---------------------------------------------------------------------------\u001b[39m",
+      "\u001b[31mIndexError\u001b[39m                                Traceback (most recent call last)",
+      "\u001b[36mCell\u001b[39m\u001b[36m \u001b[39m\u001b[32mIn[9]\u001b[39m\u001b[32m, line 6\u001b[39m\n\u001b[32m      2\u001b[39m \n\u001b[32m      3\u001b[39m count = []\n\u001b[32m      4\u001b[39m \n\u001b[32m      5\u001b[39m \u001b[38;5;28;01mfor\u001b[39;00m num \u001b[38;5;28;01min\u001b[39;00m nums:\n\u001b[32m----> \u001b[39m\u001b[32m6\u001b[39m     count[num] += \u001b[32m1\u001b[39m\n\u001b[32m      7\u001b[39m \n\u001b[32m      8\u001b[39m     \u001b[38;5;66;03m# 2. Делаем префиксную сумму\u001b[39;00m\n\u001b[32m      9\u001b[39m \u001b[38;5;28;01mfor\u001b[39;00m i \u001b[38;5;28;01min\u001b[39;00m range(\u001b[32m1\u001b[39m, \u001b[32m101\u001b[39m):\n",
+      "\u001b[31mIndexError\u001b[39m: list index out of range"
+     ]
+    }
+   ],
+   "source": [
+    "nums = [8,1,2,2,3,123,43,5,3,1,5,8,3,965,8,546,456,34,12,3]\n",
+    "\n",
+    "count = []\n",
+    "\n",
+    "for num in nums:\n",
+    "    if num in count:\n",
+    "        \n",
+    "    count[num] += 1\n",
+    "    \n",
+    "for i in range(1, 101):\n",
+    "    count[i] += count[i-1]\n",
+    "\n",
+    "result = []\n",
+    "for num in nums:\n",
+    "    if num == 0:\n",
+    "        result.append(0)\n",
+    "    else:\n",
+    "        result.append(count[num - 1])\n",
+    "\n",
+    "\n",
+    "\n",
+    "print(result)"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "LeetCode_tasks",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.14.2"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 5
+}
diff --git a/solutions/lc1.py b/solutions/lc1.py
new file mode 100644
index 0000000..23a84e2
--- /dev/null
+++ b/solutions/lc1.py
@@ -0,0 +1,9 @@
+class Solution:
+    def twoSum(self, nums: List[int], target: int) -> List[int]:
+        seen = {}
+        for i, x in enumerate(nums):
+            need = target - x
+
+            if need in seen:
+                return [seen[need], i]
+            seen[x] = i
diff --git a/solutions/lc1365.py b/solutions/lc1365.py
new file mode 100644
index 0000000..c026bec
--- /dev/null
+++ b/solutions/lc1365.py
@@ -0,0 +1,16 @@
+class Solution:
+    def smallerNumbersThanCurrent(self, nums: List[int]) -> List[int]:
+        count = {}
+        for num in nums:
+            count[num] = count.get(num, 0) + 1
+
+        sorted_nums = sorted(count)
+
+        less_count = {}
+        current = 0
+
+        for num in sorted_nums:
+            less_count[num] = current
+            current += count[num]
+
+        return [less_count[num] for num in nums]
diff --git a/solutions/lc2540.py b/solutions/lc2540.py
new file mode 100644
index 0000000..e61cc81
--- /dev/null
+++ b/solutions/lc2540.py
@@ -0,0 +1,9 @@
+class Solution:
+    def getCommon(self, nums1: List[int], nums2: List[int]) -> int:
+        s1 = set(nums1)
+
+        for num in nums2:
+            if num in s1:
+                return num
+        else:
+            return -1