foo.cc: In function 'int main()':
foo.cc:8:9: warning: unused variable 'r' [-Wunused-variable]
    8 |     int r,d,s,t;
      |         ^
foo.cc:10:10: warning: variable 'flag' set but not used [-Wunused-but-set-variable]
   10 |     bool flag = true;
      |          ^~~~

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