diff --git a/klotski/main.cc b/klotski/main.cc
index 71133d3..868daed 100644
--- a/klotski/main.cc
+++ b/klotski/main.cc
@@ -62,12 +62,14 @@ int main() {
 //    std::cout << "complete verify" << std::endl;
 
 
-    std::cout << ShortCode::code_to_string(14323231) << std::endl;
-    std::cout << ShortCode::code_from_string("EP4HZ") << std::endl;
+    for (uint32_t short_code = 0; short_code < 29334498; ++short_code) {
+        if (short_code != ShortCode::code_from_string(ShortCode::code_to_string(short_code))) {
+            std::cout << "ERROR: " << short_code << std::endl;
+        }
+    }
 
-//    for (int i = 0; i < 32; ++i) {
-//        std::cout << int(SHORT_CODE_TABLE[i] - 49) << ": " << i << std::endl;
-//    }
+//    std::cout << ShortCode::code_to_string(14323231) << std::endl;
+//    std::cout << ShortCode::code_from_string("EP4HZ") << std::endl;
 
     return 0;
 }
diff --git a/klotski/short_code.h b/klotski/short_code.h
index 44d11c2..3ea48ea 100644
--- a/klotski/short_code.h
+++ b/klotski/short_code.h
@@ -6,9 +6,11 @@
 #include <unordered_map>
 
 const char SHORT_CODE_TABLE[32] = {
-    '1', '2', '3', '4', '5', '6', '7', '8', '9',
-    'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J', 'K', 'M',
-    'N', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
+    '1', '2', '3', '4', '5', '6', '7', '8', '9', // skip `0`
+    'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', // skip `I`
+    'J', 'K', // skip `L`
+    'M', 'N', // skip `O`
+    'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
 };
 
 const char SHORT_CODE_TABLE_REV[42] = {
@@ -24,20 +26,6 @@ const char SHORT_CODE_TABLE_REV[42] = {
     26, 27, 28, 29, 30, 31,
 };
 
-// 00: 1 -> 49 (00)
-// ...
-// 08: 9 -> 57 (08)
-// 09: A -> 65 (16)
-// ...
-// 16: H -> 72 (23)
-// 17: J -> 74 (25)
-// 18: K -> 75 (26)
-// 19: M -> 77 (28)
-// 20: N -> 78 (29)
-// 21: P -> 80 (31)
-// ...
-// 31: Z -> 90 (41)
-
 class ShortCode {
 public:
     enum Mode {NORMAL, FAST};