foo.cc: In function 'int main()':
foo.cc:28:8: warning: unused variable 'b' [-Wunused-variable]
  int a,b,c,d=0,i,j,n,m,x,sum=0;
        ^
foo.cc:28:10: warning: unused variable 'c' [-Wunused-variable]
  int a,b,c,d=0,i,j,n,m,x,sum=0;
          ^

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