Add day 1 part 1

flake.nix

@@ -0,0 +1,23 @@
+{
+  description = "RGBCube's Advent of Code Solutions.";
+
+  inputs = {
+    nixpkgs = {
+      url = "github:NixOS/nixpkgs/nixos-unstable";
+    };
+  };
+
+  outputs = { nixpkgs, ... }: let
+    lib = nixpkgs.lib;
+
+    pathToResult = path: import ./${path}.nix {
+      inherit lib;
+
+      input = builtins.concatStringsSep "\n"
+        (builtins.filter (line: line != "")
+          (lib.splitString "\n" (builtins.readFile ./${path}.in)));
+    };
+  in lib.genAttrs [
+    "2023/1-1"
+  ] pathToResult;
+}