diff --git a/src/day04/solve.c b/src/day04/solve.c
index 2a123f1..f745ecd 100644
--- a/src/day04/solve.c
+++ b/src/day04/solve.c
@@ -39,22 +39,32 @@ void solve(const char *buf, size_t buf_size, Solution *result) {
 
         int_tim_sort(winning_cards, winning_cards_idx);
         int_tim_sort(mine_cards, mine_cards_idx);
-        for (int i = 0; i < winning_cards_idx; i++) {
-            printf("%d ", winning_cards[i]);
+        int i = 0, j = 0;
+        int count = 0;
+        while (i < winning_cards_idx && j < mine_cards_idx) {
+            if (winning_cards[i] == mine_cards[j]) {
+                log_debug("match: %d ", winning_cards[i]);
+                count++;
+                i++;
+                j++;
+            } else if (winning_cards[i] < mine_cards[j]) {
+                i++;
+            } else {
+                j++;
+            }
         }
-        printf("\n");
-        for (int i = 0; i < mine_cards_idx; i++) {
-            printf("%d ", mine_cards[i]);
+        if (count > 0) {
+            int score = 1 << (count - 1);
+            log_debug("count: %d, score: %d", count, score);
+            part1 += score;
         }
-        printf("\n");
-        // TODO: solve it
     }
     stbsp_snprintf(result->part1, sizeof(result->part1), "%d", part1);
     stbsp_snprintf(result->part2, sizeof(result->part2), "%d", part2);
 }
 
 int solve_input(const char *fname, Solution *result) {
-    char buf[1 << 14];
+    char buf[1 << 15];
     int n = read_input(fname, buf, sizeof(buf));
     if (n <= 0) {
         fprintf(stderr, "Failed to read %s\n", fname);
diff --git a/src/day04/solve_test.c b/src/day04/solve_test.c
index a7c5f76..2d5635d 100644
--- a/src/day04/solve_test.c
+++ b/src/day04/solve_test.c
@@ -17,11 +17,12 @@ Card 6: 31 18 13 56 72 | 74 77 10 23 35 67 36 11\n";
 }
 
 #ifdef HAVE_INPUTS
-CTEST_SKIP(day04, real) {
+CTEST(day04, real) {
     Solution solution;
     solve_input("input/" DAY ".txt", &solution);
-    ASSERT_STR("0", solution.part1);
-    ASSERT_STR("0", solution.part2);
+    ASSERT_NOT_STR("199", solution.part1); // too low
+    // ASSERT_STR("0", solution.part1);
+    // ASSERT_STR("0", solution.part2);
 }
 #endif