diff --git a/include.hh b/include.hh
index 3fa8bb2..edb7ca1 100644
--- a/include.hh
+++ b/include.hh
@@ -43,7 +43,7 @@ constexpr ull MDL2 = 87825;
 #define lsp(x) (__builtin_ctzll(ll(x)))
 
 /* arithmetic operations */
-#define mod(x, y) (((x) + (y)) % (y))
+#define mod(x, y) (((x) % (y) + (y)) % (y))
 
 /* fast pairs */
 #define upair ull
@@ -93,18 +93,6 @@ struct safe_hash {
     }
 };
 
-struct pair_hash {
-    template <typename T, typename U>
-    size_t operator()(const pair<T, U>& a) const {
-        auto hash1 = safe_hash()(a.first);
-        auto hash2 = safe_hash()(a.second);
-        if (hash1 != hash2) {
-            return hash1 ^ hash2;
-        }
-        return hash1;
-    }
-};
-
 /* build data structures */
 #define unordered_counter(from, to) __AS_PROCEDURE(unordered_map<__as_typeof(from), size_t, safe_hash> to; for (auto&& x : from) ++to[x];)
 #define counter(from, to, cmp) __AS_PROCEDURE(map<__as_typeof(from), size_t, cmp> to; for (auto&& x : from) ++to[x];)