diff --git a/04/solution_1.c b/04/solution_1.c
new file mode 100644
index 0000000..d11178a
--- /dev/null
+++ b/04/solution_1.c
@@ -0,0 +1,61 @@
+#include <stdio.h>
+
+unsigned score(signed char (*board)[5]) {
+    unsigned sum = 0;
+
+    for (unsigned r = 0; r < 5; r++) {
+        for (unsigned c = 0; c < 5; c++) {
+            if (board[r][c] > 0)
+                sum += board[r][c];
+        }
+    }
+
+    return sum;
+}
+
+int main(void) {
+    FILE *fp = fopen("input.txt", "r");
+    signed char seq[100], boards[100][5][5];
+    unsigned i, b, r, c;
+
+    for (i = 0; i < 100; i++) {
+        fscanf(fp, "%hhi%*c", &seq[i]);
+    }
+
+    for (b = 0; b < 100; b++) {
+        for (r = 0; r < 5; r++) {
+            for (c = 0; c < 5; c++)
+            fscanf(fp, "%hhi", &boards[b][r][c]);
+        }
+    }
+
+    for (i = 0; i < 100; i++) {
+        for (b = 0; b < 100; b++) {
+            for (r = 0; r < 5; r++) {
+                int rowscore = 0;
+                for (c = 0; c < 5; c++) {
+                    if (boards[b][r][c] == seq[i])
+                        boards[b][r][c] = -1;
+
+                    rowscore += boards[b][r][c];
+                }
+
+                if (rowscore == -5)
+                    goto end;
+            }
+
+            for (c = 0; c < 5; c++) {
+                int colscore = 0;
+                for (r = 0; r < 5; r++) {
+                    colscore += boards[b][r][c];
+                }
+
+                if (colscore == -5)
+                    goto end;
+            }
+        }
+    }
+
+end:
+    printf("Answer: %u\n", score(boards[b]) * seq[i]);
+}
diff --git a/04/solution_2.c b/04/solution_2.c
new file mode 100644
index 0000000..33083e3
--- /dev/null
+++ b/04/solution_2.c
@@ -0,0 +1,67 @@
+#include <stdio.h>
+
+unsigned score(signed char (*board)[5]) {
+    unsigned sum = 0;
+
+    for (unsigned r = 0; r < 5; r++) {
+        for (unsigned c = 0; c < 5; c++) {
+            if (board[r][c] > 0)
+                sum += board[r][c];
+        }
+    }
+
+    return sum;
+}
+
+int main(void) {
+    FILE *fp = fopen("input.txt", "r");
+    signed char seq[100], boards[100][5][5];
+    unsigned i, b, r, c, lastwin;
+
+    for (i = 0; i < 100; i++) {
+        fscanf(fp, "%hhi%*c", &seq[i]);
+    }
+
+    for (b = 0; b < 100; b++) {
+        for (r = 0; r < 5; r++) {
+            for (c = 0; c < 5; c++)
+            fscanf(fp, "%hhi", &boards[b][r][c]);
+        }
+    }
+
+    for (i = 0; i < 100; i++) {
+        for (b = 0; b < 100; b++) {
+            if (boards[b][0][0] == -2)
+                continue;
+
+            for (r = 0; r < 5; r++) {
+                int rowscore = 0;
+                for (c = 0; c < 5; c++) {
+                    if (boards[b][r][c] == seq[i])
+                        boards[b][r][c] = -1;
+
+                    rowscore += boards[b][r][c];
+                }
+
+                if (rowscore == -5)
+                    goto win;
+            }
+
+            for (c = 0; c < 5; c++) {
+                int colscore = 0;
+                for (r = 0; r < 5; r++) {
+                    colscore += boards[b][r][c];
+                }
+
+                if (colscore == -5)
+                    goto win;
+            }
+            continue;
+win:
+            lastwin = score(boards[b]) * seq[i];
+            boards[b][0][0] = -2;
+        }
+    }
+
+    printf("Answer: %u\n", lastwin);
+}