diff --git a/main.cpp b/main.cpp
index 5088524..b2eb0a4 100644
--- a/main.cpp
+++ b/main.cpp
@@ -105,7 +105,9 @@ vector< MyMatrix > get_good_matrices() {
     vector< MyMatrix > res;
     for (size_t cur_val = 1ll << (ARGS_COUNT * ARGS_COUNT); cur_val != 0; --cur_val) {
         MyMatrix cur_matrix(cur_val);
-        if ( cur_matrix.get_determinant() != 0 )
+        Storage det = cur_matrix.get_determinant();
+        // if ( det %2 != 0 )
+        if ( det == 1 or det == Storage(-1) )
             res.push_back(cur_matrix);
     }
     return res;