diff --git a/dat/24/ex/03b.txt b/dat/24/ex/03b.txt
new file mode 100644
index 0000000..30032cb
--- /dev/null
+++ b/dat/24/ex/03b.txt
@@ -0,0 +1 @@
+xmul(2,4)&mul[3,7]!^don't()_mul(5,5)+mul(32,64](mul(11,8)undo()?mul(8,5))
diff --git a/sol/24/day03.cpp b/sol/24/day03.cpp
index 7978a7e..720f85e 100644
--- a/sol/24/day03.cpp
+++ b/sol/24/day03.cpp
@@ -111,7 +111,7 @@ public:
 
 public:
     inline static auto is_identifier(std::string_view const& str) -> bool {
-        return ctre::match<"^[a-z]+$">(str);
+        return ctre::match<"^[a-z']+$">(str);
     }
 
     inline static auto is_numeric_literal(std::string_view const& str) -> bool {
@@ -163,15 +163,15 @@ private:
             return token(str, type, token_type_category(type), m_line, col);
         }
 
-        if (peek() == 'm') {
+        // mul, do, don't identifier
+        if (peek() == 'm' || peek() == 'd') {
             auto const is_valid_identifier_char = [](auto const c) {
-                return c >= 'a' && c <= 'z';
+                return (c >= 'a' && c <= 'z') || c == '\'';
             };
             while (is_valid_identifier_char(peek())) str += peek_consume();
             auto const check_type = [](auto const str) {
                 if (!token::is_identifier(str)) return token_type::invalid;
-                if (str == "mul") return token_type::identifier;
-                return token_type::invalid;
+                return token_type::identifier;
             };
             auto const& type = check_type(str);
             return token(str, type, token_type_category(type), m_line, col);
@@ -236,7 +236,7 @@ private:
         return static_cast<char>(m_strm.get());
     }
     auto has_next() const -> bool {
-        return !m_strm.eof();
+        return !m_strm.eof() && m_strm.good();
     }
 
 private:
@@ -279,6 +279,7 @@ public:
 
 private:
     auto call_expression_str() const -> std::string {
+        if (m_nodes.size() == 0) return "";
         using namespace std::string_literals;
         std::string str{", ["};
         for (std::size_t i = 0; i < m_nodes.size(); ++i) {
@@ -392,14 +393,50 @@ auto aoc::entry([[maybe_unused]]std::vector<std::string_view> const& args) -> vo
     auto const tokens = lexer.tokenize();
     auto const nodes = parser.parse(tokens);
 
-    auto op = nodes | std::views::transform([](auto const& node) {
+    // for (auto const& token : tokens) {
+    //     fmt::print("{}\n", token.str());
+    // }
+    //
+    // for (auto const& node : nodes) {
+    //     fmt::print("{}\n", node.str());
+    // }
+
+    auto opa = nodes | std::views::filter([](auto const& node) {
+            return node.value() == "mul";
+        }) | std::views::transform([](auto const& node) {
             auto const a = std::stoi(node.nodes()[0].value());
             auto const b = std::stoi(node.nodes()[1].value());
             return a * b;
         });
 
-    auto const sum = std::accumulate(std::begin(op), std::end(op), 0);
+    auto const sum = std::accumulate(std::begin(opa), std::end(opa), 0);
 
     fmt::print("Part A: {}\n", sum);
+
+    std::vector<npr::node> program{};
+    bool is_do = true;
+    for (auto const& node : nodes) {
+        if (node.value() == "do") {
+            is_do = true;
+            continue;
+        }
+        if (node.value() == "don't") {
+            is_do = false;
+            continue;
+        }
+        if (is_do) program.push_back(node);
+    }
+
+    auto opb = program | std::views::filter([](auto const& node) {
+            return node.value() == "mul";
+        }) | std::views::transform([](auto const& node) {
+            auto const a = std::stoi(node.nodes()[0].value());
+            auto const b = std::stoi(node.nodes()[1].value());
+            return a * b;
+        });
+
+    auto const sumb = std::accumulate(std::begin(opb), std::end(opb), 0);
+
+    fmt::print("Part B: {}\n", sumb);
 }