diff --git a/day-4/package.json b/day-4/package.json
index cf79837..8d37395 100644
--- a/day-4/package.json
+++ b/day-4/package.json
@@ -17,7 +17,7 @@
     "@types/jest": "^26.0.10",
     "@types/node": "^14.11.8",
     "@typescript-eslint/eslint-plugin": "^4.7.0",
-    "@typescript-eslint/parser": "^4.7.0",
+    "@typescript-eslint/parser": "^4.9.1",
     "eslint": "^7.13.0",
     "eslint-config-prettier": "^6.11.0",
     "eslint-import-resolver-typescript": "^2.2.1",
diff --git a/day-4/yarn.lock b/day-4/yarn.lock
index 59d8b0a..4dc64e5 100644
--- a/day-4/yarn.lock
+++ b/day-4/yarn.lock
@@ -662,14 +662,14 @@
     eslint-scope "^5.0.0"
     eslint-utils "^2.0.0"
 
-"@typescript-eslint/parser@^4.7.0":
-  version "4.7.0"
-  resolved "https://registry.yarnpkg.com/@typescript-eslint/parser/-/parser-4.7.0.tgz#44bdab0f788b478178368baa65d3365fdc63da1c"
-  integrity sha512-+meGV8bMP1sJHBI2AFq1GeTwofcGiur8LoIr6v+rEmD9knyCqDlrQcFHR0KDDfldHIFDU/enZ53fla6ReF4wRw==
-  dependencies:
-    "@typescript-eslint/scope-manager" "4.7.0"
-    "@typescript-eslint/types" "4.7.0"
-    "@typescript-eslint/typescript-estree" "4.7.0"
+"@typescript-eslint/parser@^4.9.1":
+  version "4.9.1"
+  resolved "https://registry.yarnpkg.com/@typescript-eslint/parser/-/parser-4.9.1.tgz#2d74c4db5dd5117379a9659081a4d1ec02629055"
+  integrity sha512-Gv2VpqiomvQ2v4UL+dXlQcZ8zCX4eTkoIW+1aGVWT6yTO+6jbxsw7yQl2z2pPl/4B9qa5JXeIbhJpONKjXIy3g==
+  dependencies:
+    "@typescript-eslint/scope-manager" "4.9.1"
+    "@typescript-eslint/types" "4.9.1"
+    "@typescript-eslint/typescript-estree" "4.9.1"
     debug "^4.1.1"
 
 "@typescript-eslint/scope-manager@4.7.0":
@@ -680,11 +680,24 @@
     "@typescript-eslint/types" "4.7.0"
     "@typescript-eslint/visitor-keys" "4.7.0"
 
+"@typescript-eslint/scope-manager@4.9.1":
+  version "4.9.1"
+  resolved "https://registry.yarnpkg.com/@typescript-eslint/scope-manager/-/scope-manager-4.9.1.tgz#cc2fde310b3f3deafe8436a924e784eaab265103"
+  integrity sha512-sa4L9yUfD/1sg9Kl8OxPxvpUcqxKXRjBeZxBuZSSV1v13hjfEJkn84n0An2hN8oLQ1PmEl2uA6FkI07idXeFgQ==
+  dependencies:
+    "@typescript-eslint/types" "4.9.1"
+    "@typescript-eslint/visitor-keys" "4.9.1"
+
 "@typescript-eslint/types@4.7.0":
   version "4.7.0"
   resolved "https://registry.yarnpkg.com/@typescript-eslint/types/-/types-4.7.0.tgz#5e95ef5c740f43d942542b35811f87b62fccca69"
   integrity sha512-uLszFe0wExJc+I7q0Z/+BnP7wao/kzX0hB5vJn4LIgrfrMLgnB2UXoReV19lkJQS1a1mHWGGODSxnBx6JQC3Sg==
 
+"@typescript-eslint/types@4.9.1":
+  version "4.9.1"
+  resolved "https://registry.yarnpkg.com/@typescript-eslint/types/-/types-4.9.1.tgz#a1a7dd80e4e5ac2c593bc458d75dd1edaf77faa2"
+  integrity sha512-fjkT+tXR13ks6Le7JiEdagnwEFc49IkOyys7ueWQ4O8k4quKPwPJudrwlVOJCUQhXo45PrfIvIarcrEjFTNwUA==
+
 "@typescript-eslint/typescript-estree@4.7.0":
   version "4.7.0"
   resolved "https://registry.yarnpkg.com/@typescript-eslint/typescript-estree/-/typescript-estree-4.7.0.tgz#539531167f05ba20eb0b6785567076679e29d393"
@@ -699,6 +712,20 @@
     semver "^7.3.2"
     tsutils "^3.17.1"
 
+"@typescript-eslint/typescript-estree@4.9.1":
+  version "4.9.1"
+  resolved "https://registry.yarnpkg.com/@typescript-eslint/typescript-estree/-/typescript-estree-4.9.1.tgz#6e5b86ff5a5f66809e1f347469fadeec69ac50bf"
+  integrity sha512-bzP8vqwX6Vgmvs81bPtCkLtM/Skh36NE6unu6tsDeU/ZFoYthlTXbBmpIrvosgiDKlWTfb2ZpPELHH89aQjeQw==
+  dependencies:
+    "@typescript-eslint/types" "4.9.1"
+    "@typescript-eslint/visitor-keys" "4.9.1"
+    debug "^4.1.1"
+    globby "^11.0.1"
+    is-glob "^4.0.1"
+    lodash "^4.17.15"
+    semver "^7.3.2"
+    tsutils "^3.17.1"
+
 "@typescript-eslint/visitor-keys@4.7.0":
   version "4.7.0"
   resolved "https://registry.yarnpkg.com/@typescript-eslint/visitor-keys/-/visitor-keys-4.7.0.tgz#6783824f22acfc49e754970ed21b88ac03b80e6f"
@@ -707,6 +734,14 @@
     "@typescript-eslint/types" "4.7.0"
     eslint-visitor-keys "^2.0.0"
 
+"@typescript-eslint/visitor-keys@4.9.1":
+  version "4.9.1"
+  resolved "https://registry.yarnpkg.com/@typescript-eslint/visitor-keys/-/visitor-keys-4.9.1.tgz#d76374a58c4ead9e92b454d186fea63487b25ae1"
+  integrity sha512-9gspzc6UqLQHd7lXQS7oWs+hrYggspv/rk6zzEMhCbYwPE/sF7oxo7GAjkS35Tdlt7wguIG+ViWCPtVZHz/ybQ==
+  dependencies:
+    "@typescript-eslint/types" "4.9.1"
+    eslint-visitor-keys "^2.0.0"
+
 abab@^2.0.3:
   version "2.0.5"
   resolved "https://registry.yarnpkg.com/abab/-/abab-2.0.5.tgz#c0b678fb32d60fc1219c784d6a826fe385aeb79a"