foo.cc: In function 'int main()':
foo.cc:6:12: warning: variable 'c' set but not used [-Wunused-but-set-variable]
    6 |  int a,b=0,c,d;
      |            ^
foo.cc:6:14: warning: unused variable 'd' [-Wunused-variable]
    6 |  int a,b=0,c,d;
      |              ^

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