/in/foo.cc: In function 'int main()':
/in/foo.cc:13:19: error: 'total_energy' was not declared in this scope
   13 |     double 电费 = total_energy - m;
      |                   ^~~~~~~~~~~~
/in/foo.cc:11:12: warning: unused variable '\U0000603b\U00007535\U000091cf' [-Wunused-variable]
   11 |     double 总电量 = a / 20.0;
      |            ^~~~~~