/in/foo.cc: In function 'int main()':
/in/foo.cc:11:15: warning: left operand of comma operator has no effect [-Wunused-value]
   11 |     else if (x>=500,x<1000)
      |              ~^~~~~
/in/foo.cc:15:15: warning: left operand of comma operator has no effect [-Wunused-value]
   15 |     else if (x>=1000,x<1500)
      |              ~^~~~~~
/in/foo.cc:19:15: warning: left operand of comma operator has no effect [-Wunused-value]
   19 |     else if (x>=1500,x<2000)
      |              ~^~~~~~