diff --git a/main.py b/main.py
index 75322d8..7e068c4 100755
--- a/main.py
+++ b/main.py
@@ -104,5 +104,16 @@ if __name__ == "__main__":
     #     if matches(e, constraints):
     #         draw(solution, width, pattern)
 
+    fixed = []
     for sol in solve2(width, pattern, constraints):
+        exp = list(expand_solution(sol, width, pattern))
+        if len(fixed) == 0:
+            fixed = exp
+        else:
+            for i,e in enumerate(exp):
+                if fixed[i] != e:
+                    fixed[i] = -1
         draw(sol, width, pattern)
+
+    print("invariants:")
+    print("".join({1:'\N{LEFT SEVEN EIGHTHS BLOCK}',0:'.',-1:'?'}[x] for x in fixed))