diff --git a/2021-08/2021-08-26 (day39)/README.md b/2021-08/2021-08-26 (day39)/README.md
new file mode 100644
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@@ -0,0 +1,57 @@
+# 70. Climbing Stairs
+
+`Easy`
+
+## Description
+
+<p>You are climbing a staircase. It takes <code>n</code> steps to reach the top.</p>
+
+<p>Each time you can either climb <code>1</code> or <code>2</code> steps. In how many distinct ways can you climb to the top?</p>
+
+<p>&nbsp;</p>
+<p><strong>Example 1:</strong></p>
+
+<pre>
+<strong>Input:</strong> n = 2
+<strong>Output:</strong> 2
+<strong>Explanation:</strong> There are two ways to climb to the top.
+1. 1 step + 1 step
+2. 2 steps
+</pre>
+
+<p><strong>Example 2:</strong></p>
+
+<pre>
+<strong>Input:</strong> n = 3
+<strong>Output:</strong> 3
+<strong>Explanation:</strong> There are three ways to climb to the top.
+1. 1 step + 1 step + 1 step
+2. 1 step + 2 steps
+3. 2 steps + 1 step
+</pre>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>1 &lt;= n &lt;= 45</code></li>
+</ul>
+
+
+---
+
+### Topic Tags
+
+[math]: https://img.shields.io/badge/-Math-EF9A9A
+[dynamic-programming]: https://img.shields.io/badge/-Dynamic%20Programming-B39DDB
+[memoization]: https://img.shields.io/badge/-Memoization-81D4FA
+
+![Math][math]
+
+![Dynamic Programming][dynamic-programming]
+
+![Memoization][memoization]
+
+---
+
+##### [original question](https://leetcode.com/problems/climbing-stairs)
diff --git a/README.md b/README.md
index 52570b1d..acaafdb0 100644
--- a/README.md
+++ b/README.md
@@ -47,6 +47,7 @@
 | 036 | [121][0121] | [Best Time to Buy and Sell Stock](<./2021-08/2021-08-23%20(day36)>) | ![Easy][Easy] | Array; Dynamic Programming | 
 | 037 | [122][0122] | [Best Time to Buy and Sell Stock II](<./2021-08/2021-08-24%20(day37)>) | ![Easy][Easy] | Array; Dynamic Programming; Greedy | 
 | 038 | [123][0123] | [Best Time to Buy and Sell Stock III](<./2021-08/2021-08-25%20(day38)>) | ![Hard][Hard] | Array; Dynamic Programming | 
+| 039 | [70][0070] | [Climbing Stairs](<./2021-08/2021-08-26%20(day39)>) | ![Easy][Easy] | Math; Dynamic Programming; Memoization | 
 
 
 
@@ -54,7 +55,7 @@
 
 ### Summary
 
-![](https://img.shields.io/badge/Easy-21-brightgreen)
+![](https://img.shields.io/badge/Easy-22-brightgreen)
 
 ![](https://img.shields.io/badge/Medium-14-orange)
 
@@ -81,6 +82,7 @@
 [0048]: https://leetcode.com/problems/rotate-image/
 [0049]: https://leetcode.com/problems/group-anagrams/
 [0064]: https://leetcode.com/problems/minimum-path-sum/
+[0070]: https://leetcode.com/problems/climbing-stairs/
 [0083]: https://leetcode.com/problems/remove-duplicates-from-sorted-list/
 [0094]: https://leetcode.com/problems/binary-tree-inorder-traversal/
 [0098]: https://leetcode.com/problems/validate-binary-search-tree/
diff --git a/problem_list.log b/problem_list.log
index d4de710d..abeebbc0 100644
--- a/problem_list.log
+++ b/problem_list.log
@@ -37,3 +37,4 @@
 36,121,https://leetcode.com/problems/best-time-to-buy-and-sell-stock/,2021-08-23,Best Time to Buy and Sell Stock,Easy,Array;Dynamic Programming
 37,122,https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii/,2021-08-24,Best Time to Buy and Sell Stock II,Easy,Array;Dynamic Programming;Greedy
 38,123,https://leetcode.com/problems/best-time-to-buy-and-sell-stock-iii/,2021-08-25,Best Time to Buy and Sell Stock III,Hard,Array;Dynamic Programming
+39,70,https://leetcode.com/problems/climbing-stairs/,2021-08-26,Climbing Stairs,Easy,Math;Dynamic Programming;Memoization