/in/foo.cc: In function 'int main()':
/in/foo.cc:10:11: warning: left operand of comma operator has no effect [-Wunused-value]
   10 |     if (a >= 500, a < 1000)
      |         ~~^~~~~~
/in/foo.cc:15:16: warning: left operand of comma operator has no effect [-Wunused-value]
   15 |     else if (a >= 1000, a < 1500)
      |              ~~^~~~~~~
/in/foo.cc:20:16: warning: left operand of comma operator has no effect [-Wunused-value]
   20 |     else if (a >= 1500, a < 2000)
      |              ~~^~~~~~~
/in/foo.cc:30:16: warning: left operand of comma operator has no effect [-Wunused-value]
   30 |     else if (a >= 0, a < 500)
      |              ~~^~~~