diff --git a/aoc/aoc.c b/aoc/aoc.c
index 4b14992..7715d4b 100644
--- a/aoc/aoc.c
+++ b/aoc/aoc.c
@@ -70,3 +70,19 @@ parse_i64(str s, Arena temp) {
     ASSERT(*endptr == '\0');
     return result;
 }
+
+Grid parse_grid(str input, Arena *arena) {
+    Tokens lines = str_tokenize(arena, input, STR("\n"));
+    ASSERT(lines.len > 0);
+    i32 width = lines.tokens[0].len;
+    for (i32 i = 0; i < lines.len; i++) {
+        ASSERT(lines.tokens[i].len == width);
+    }
+
+    Grid grid = { .width = width, .height = lines.len };
+    grid.grid = ARENA_ALLOC_ARRAY(arena, u8, grid.width * grid.height);
+    for (i32 i = 0; i < lines.len; i++) {
+        memcpy(grid.grid + i * grid.width, lines.tokens[i].data, grid.width);
+    }
+    return grid;
+}
diff --git a/aoc/aoc.h b/aoc/aoc.h
index cad676d..1245781 100644
--- a/aoc/aoc.h
+++ b/aoc/aoc.h
@@ -17,6 +17,18 @@ Tokens read_lines(Arena *arena, const char *path);
 char *str_to_cstr(str s, Arena *a);
 i64 parse_i64(str s, Arena temp);
 
+typedef struct Grid {
+    u8 *grid;
+    i32 width, height;
+} Grid;
+
+Grid parse_grid(str input, Arena *arena);
+static inline u8
+grid_at(Grid *grid, i32 x, i32 y) {
+    return grid->grid[y * grid->width + x];
+}
+
+
 #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
 #include <stdio.h>
 #define ASSERT(cond) if (!(cond)) { fprintf(stderr, "%s:%d (%s): Assertion failed: %s\n", __FILE__, __LINE__, __func__, #cond); __builtin_trap(); }