diff --git a/.gitignore b/.gitignore
index 0e7fb71..7d0f294 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,11 @@
+# ClangD
+.cache
+
+# Nix files
+.direnv
+
 # Output folders
+build/
 output/
 
 # Vimspector
diff --git a/02/.envrc b/02/.envrc
new file mode 100644
index 0000000..1d953f4
--- /dev/null
+++ b/02/.envrc
@@ -0,0 +1 @@
+use nix
diff --git a/02/.gitignore b/02/.gitignore
index bd461b5..9ae5e67 100644
--- a/02/.gitignore
+++ b/02/.gitignore
@@ -1,3 +1,15 @@
+# ClangD
+.cache
+
+# Nix files
+.direnv
+
+# Output folders
+output/
+
+# Vimspector
+# .vimspector.json
+
 # Prerequisites
 *.d
 
@@ -50,25 +62,3 @@ modules.order
 Module.symvers
 Mkfile.old
 dkms.conf
-
-# Vscode
-.vscode/
-
-# CMake
-CMakeLists.txt.user
-CMakeCache.txt
-CMakeFiles
-CMakeScripts
-Testing
-Makefile
-cmake_install.cmake
-install_manifest.txt
-compile_commands.json
-.cache/
-CTestTestfile.cmake
-_deps
-build/
-lib/
-bin/
-*.swp
-
diff --git a/02/default.nix b/02/default.nix
new file mode 100644
index 0000000..17a2804
--- /dev/null
+++ b/02/default.nix
@@ -0,0 +1,12 @@
+let
+  pkgs = import <nixpkgs> {};
+in
+pkgs.mkShell {
+  packages = with pkgs; [
+    # Choose the build tools that you need
+    gcc
+    gdb
+    cmake
+  ];
+}
+
diff --git a/02/src/main.c b/02/src/main.c
index 70ba1e7..efb8133 100644
--- a/02/src/main.c
+++ b/02/src/main.c
@@ -6,20 +6,132 @@
  * @author jiriks74
  */
 
+#include <stdbool.h>
 #include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
 
+const int MAX_RED = 12;
+const int MAX_GREEN = 13;
+const int MAX_BLUE = 14;
+
+typedef struct {
+  int red;
+  int green;
+  int blue;
+} GameShow;
+
+/**
+ * @brief Count how many cubes of each color were in a show
+ * @param *show A show of cubes in a game
+ * @return A count of all the cubes in a struct
+ */
+GameShow get_max_cube_counts(char *game) {
+  char *curr = game;
+  GameShow result = {0};
+
+  while (curr != NULL) {
+    char *end_show = strchr(curr, ';');
+
+    if (end_show != NULL) {
+      *end_show = '\0';
+    }
+
+    while (curr != NULL) {
+      int cube_count = atoi(curr);
+
+      curr = strchr(curr, ' ');
+      curr += sizeof(char);
+
+      if (*curr == 'r') {
+        if (cube_count > result.red)
+          result.red = cube_count;
+      } else if (*curr == 'g') {
+        if (cube_count > result.green)
+          result.green = cube_count;
+      } else if (*curr == 'b') {
+        if (cube_count > result.blue)
+          result.blue = cube_count;
+      } else {
+        result.red = -1;
+        result.green = -1;
+        result.blue = -1;
+        return result;
+      }
+      curr = strchr(curr, ',');
+      if (curr != NULL)
+        curr += sizeof(char) * 2;
+    }
+
+    if (end_show != NULL) {
+      *end_show = ';';
+      curr = end_show + sizeof(char) * 2;
+    } else
+      curr = end_show;
+  }
+  return result;
+}
+
+/**
+ * @brief Count how many times were the cubes shown
+ * @return Number of shows or -1 when error occurs
+ */
+bool is_game_possible(char *game) {
+  // char *curr = strchr(game, ':');
+  // curr += sizeof(char) * 2;
+
+  // if (curr == NULL) {
+  //   return false;
+  // }
+
+  GameShow show_counts = get_max_cube_counts(game);
+
+  if (show_counts.red > MAX_RED)
+    return false;
+  else if (show_counts.green > MAX_GREEN)
+    return false;
+  else if (show_counts.blue > MAX_BLUE)
+    return false;
+
+  return true;
+}
+
+#ifndef TESTING
 /**
  * @brief Main entry point
  * @param argc Number of command-line arguments.
  * @param argv Array of command-line arguments.
  */
-#ifndef TESTING
 int main(int argc, char *argv[])
 #endif
 #ifdef TESTING
     int main_test(int argc, char *argv[])
 #endif
 {
-  printf("Hello world!\n");
+  FILE *input = fopen(argv[1], "r");
+
+  int possible_game_ids_sum = 0;
+  int sum_of_powers = 0;
+
+  char line[512];
+  while (fgets(line, sizeof(line), input)) {
+    if (*line != 'G')
+      break;
+
+    int curr_game_id = atoi(line + sizeof("Game"));
+
+    // if (is_game_possible(line)) {
+    if (is_game_possible(strchr(line, ':') + sizeof(char) * 2)) {
+      possible_game_ids_sum += curr_game_id;
+      // printf("Game %d is possible\n", curr_game_id);
+    } // else
+      // printf("Game %d is impossible\n", curr_game_id);
+    GameShow min_cubes =
+        get_max_cube_counts(strchr(line, ':') + sizeof(char) * 2);
+    sum_of_powers += min_cubes.red * min_cubes.green * min_cubes.blue;
+  }
+
+  printf("Sum of possible game IDs: %d\n", possible_game_ids_sum);
+  printf("Sum of powers:            %d\n", sum_of_powers);
   return 0;
 }
diff --git a/02/test.input b/02/test.input
new file mode 100644
index 0000000..295c36d
--- /dev/null
+++ b/02/test.input
@@ -0,0 +1,5 @@
+Game 1: 3 blue, 4 red; 1 red, 2 green, 6 blue; 2 green
+Game 2: 1 blue, 2 green; 3 green, 4 blue, 1 red; 1 green, 1 blue
+Game 3: 8 green, 6 blue, 20 red; 5 blue, 4 red, 13 green; 5 green, 1 red
+Game 4: 1 green, 3 red, 6 blue; 3 green, 6 red; 3 green, 15 blue, 14 red
+Game 5: 6 red, 1 blue, 3 green; 2 blue, 1 red, 2 green