foo.cc: In function 'int main()':
foo.cc:8:13: warning: unused variable 'b' [-Wunused-variable]
  int n,a[N],b[N]={0},all,max,i,j,k,x=0;
             ^
foo.cc:8:34: warning: unused variable 'k' [-Wunused-variable]
  int n,a[N],b[N]={0},all,max,i,j,k,x=0;
                                  ^

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