Update README.md

Author: AliOsm

CodeForces/README.md

@@ -599,3 +599,20 @@
 - [1157C2. Increasing Subsequence (hard version)](http://codeforces.com/contest/1157/problem/C2)
 - [1157D. N Problems During K Days](http://codeforces.com/contest/1157/problem/D)
 - [1157E. Minimum Array](http://codeforces.com/contest/1157/problem/E)
+- [1213A. Chips Moving](https://codeforces.com/contest/1213/problem/A)
+- [1213B. Bad Prices](https://codeforces.com/contest/1213/problem/B)
+- [1213C. Book Reading](https://codeforces.com/contest/1213/problem/C)
+- [1213D1. Equalizing by Division (easy version)](https://codeforces.com/contest/1213/problem/D1)
+- [1213D2. Equalizing by Division (hard version)](https://codeforces.com/contest/1213/problem/D2)
+- [1213E. Two Small Strings](https://codeforces.com/contest/1213/problem/E)
+- [1216A. Prefixes](https://codeforces.com/contest/1216/problem/A)
+- [1216B. Shooting](https://codeforces.com/contest/1216/problem/B)
+- [1216C. White Sheet](https://codeforces.com/contest/1216/problem/C)
+- [1216D. Swords](https://codeforces.com/contest/1216/problem/D)
+- [1216E1. Numerical Sequence (easy version)](https://codeforces.com/contest/1216/problem/E1)
+- [1216E2. Numerical Sequence (hard version)](https://codeforces.com/contest/1216/problem/E2)
+- [1234A. Equalize Prices Again](https://codeforces.com/contest/1234/problem/A)
+- [1234B1. Social Network (easy version)](https://codeforces.com/contest/1234/problem/B1)
+- [1234B2. Social Network (hard version)](https://codeforces.com/contest/1234/problem/B2)
+- [1234C. Pipes](https://codeforces.com/contest/1234/problem/C)
+- [1234D. Distinct Characters Queries](https://codeforces.com/contest/1234/problem/D)