diff --git a/2022/04.cpp b/2022/04.cpp
new file mode 100644
index 0000000..2d93bae
--- /dev/null
+++ b/2022/04.cpp
@@ -0,0 +1,55 @@
+#include <cstddef>
+#include <cstdio>
+#include <iostream>
+#include <sstream>
+#include <stdexcept>
+#include <string>
+#include <tuple>
+
+#include <doctest.h>
+
+#include <aocpp/Startup.hpp>
+
+namespace {
+
+auto Solve(std::istream & in) -> std::pair<std::size_t, std::size_t>
+{
+  std::size_t p1{0}, p2{0};
+  std::string line;
+  while (std::getline(in, line)) {
+    unsigned a,b,c,d;
+    if (4 != std::sscanf(line.c_str(), "%u-%u,%u-%u\n", &a, &b, &c, &d)) {
+      throw std::runtime_error{"bad input"};
+    }
+    
+    if (a <= c && d <= b || c <= a && b <= d) p1++;
+    
+    if (a <= c && c <= b || a <= d && d <= b ||
+        c <= a && a <= d || c <= b && b <= d) p2++;
+  }
+  return {p1, p2};
+}
+
+
+} // namespace
+
+TEST_SUITE("2022-04 examples") {
+  TEST_CASE("example") {
+    std::istringstream in {
+      "2-4,6-8\n"
+      "2-3,4-5\n"
+      "5-7,7-9\n"
+      "2-8,3-7\n"
+      "6-6,4-6\n"
+      "2-6,4-8\n"};
+    auto [p1,p2] = Solve(in);
+    CHECK(p1 == 2);
+    CHECK(p2 == 4);
+  }
+}
+
+auto main(int argc, char** argv) -> int {
+  auto [p1,p2] = Solve(*aocpp::Startup(argc, argv));
+  std::cout << "Part 1: " << p1 << std::endl;
+  std::cout << "Part 2: " << p2 << std::endl;
+}
diff --git a/2022/CMakeLists.txt b/2022/CMakeLists.txt
index d4d59db..96e23bb 100644
--- a/2022/CMakeLists.txt
+++ b/2022/CMakeLists.txt
@@ -1,2 +1,5 @@
 add_executable(2022_01 01.cpp)
 target_link_libraries(2022_01 aocpp)
+
+add_executable(2022_04 04.cpp)
+target_link_libraries(2022_04 aocpp)