Index: aoc2024.c
==================================================================
--- aoc2024.c
+++ aoc2024.c
@@ -6,13 +6,28 @@
 #include <string.h>
 #include "aocdailies.h"
 #include "aocutils.h"
 
 void aoc202405(char *data, size_t len) {
-    (void)data; // unused argument
     (void)len; // unused argument
-    printf("wip/n");
+    // assume (by visual inspection) all page numbers `pn` are between 10 and 99
+    unsigned pagepair[2500][2], npp = 0;
+    char *line = strtok(data, "\n");
+    while (strchr(line, '|')) {
+        char *err;
+        pagepair[npp][0] = strtoul(line, &err, 10);
+        err += 1; // skip '|'
+        pagepair[npp][1] = strtoul(line, &err, 10);
+        npp++;
+        line = strtok(NULL, "\n");
+    }
+    printf("first pagepair: %u and %u\n", pagepair[0][0], pagepair[0][1]);
+    printf("last pagepair: %u and %u\n", pagepair[npp - 1][0], pagepair[npp - 1][1]);
+    printf("got %u pairs\n", npp);
+    while ((line = strtok(NULL, "\n")) != NULL) {
+        // process line
+    }
 }
 static size_t rcmap(unsigned size, unsigned row, unsigned col) {
     return row * (size + 1) + col;
 }