foo.c: In function 'main':
foo.c:5:7: warning: left-hand operand of comma expression has no effect [-Wunused-value]
    5 |  for(a,b,s=0;a<=b;a++)
      |       ^
foo.c:5:9: warning: left-hand operand of comma expression has no effect [-Wunused-value]
    5 |  for(a,b,s=0;a<=b;a++)
      |         ^

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