auto update README.md

Author: CheChe903

README.md

@@ -52,6 +52,7 @@
 |12851. 숨바꼭질 2|[링크](./%EB%B0%B1%EC%A4%80/Gold/12851.%E2%80%85%EC%88%A8%EB%B0%94%EA%BC%AD%EC%A7%88%E2%80%852/%EC%88%A8%EB%B0%94%EA%BC%AD%EC%A7%88%E2%80%852.java)|
 |12865. 평범한 배낭|[링크](./%EB%B0%B1%EC%A4%80/Gold/12865.%E2%80%85%ED%8F%89%EB%B2%94%ED%95%9C%E2%80%85%EB%B0%B0%EB%82%AD/README.md)|
 |12869. 뮤탈리스크|[링크](./%EB%B0%B1%EC%A4%80/Gold/12869.%E2%80%85%EB%AE%A4%ED%83%88%EB%A6%AC%EC%8A%A4%ED%81%AC/README.md)|
+|12904. A와 B|[링크](./%EB%B0%B1%EC%A4%80/Gold/12904.%E2%80%85A%EC%99%80%E2%80%85B/A%EC%99%80%E2%80%85B.java)|
 |13023. ABCDE|[링크](./%EB%B0%B1%EC%A4%80/Gold/13023.%E2%80%85ABCDE/ABCDE.java)|
 |13144. List of Unique Numbers|[링크](./%EB%B0%B1%EC%A4%80/Gold/13144.%E2%80%85List%E2%80%85of%E2%80%85Unique%E2%80%85Numbers/README.md)|
 |13398. 연속합 2|[링크](./%EB%B0%B1%EC%A4%80/Gold/13398.%E2%80%85%EC%97%B0%EC%86%8D%ED%95%A9%E2%80%852/README.md)|