foo.c: In function 'main':
foo.c:15:9: warning: 'd' may be used uninitialized [-Wmaybe-uninitialized]
   15 |         printf("%d\n", d);
      |         ^~~~~~~~~~~~~~~~~
foo.c:5:14: note: 'd' was declared here
    5 |     int a, b,d;
      |              ^

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