foo.cc: In function 'int main()':
foo.cc:7:8: warning: unused variable 'd' [-Wunused-variable]
    7 |  int n,d,i,x;
      |        ^
foo.cc:8:12: warning: unused variable 'c' [-Wunused-variable]
    8 |  float a,b,c;
      |            ^

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