foo.c: In function 'main':
foo.c:9:20: error: expected expression before ')' token
    9 |         if (a == + )
      |                    ^
foo.c:11:20: error: expected expression before ')' token
   11 |         if (a == - )
      |                    ^
foo.c:13:16: warning: too many arguments for format [-Wformat-extra-args]
   13 |         printf("&d",sum);
      |                ^~~~

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