z3 compat

2022/21.cpp

@@ -163,10 +163,12 @@ auto Part2(Input const& input) -> std::int64_t
       solver.add(constants.at(entry.lvalue) == rhs);
     }
   }
+
   if (solver.check() != z3::sat) {
     throw std::runtime_error{"no solution to part 2"};
   }
-  return solver.get_model().eval(constants.at("humn")).as_int64();
+
+  return solver.get_model().eval(constants.at("humn")).get_numeral_int64();
 }
 
 } // namespace