foo.cc: In function 'int main()':
foo.cc:6:20: warning: unused variable 'x' [-Wunused-variable]
  int a[N],b[N]={0},x;
                    ^
foo.cc:7:8: warning: variable 'j' set but not used [-Wunused-but-set-variable]
  int i,j,max;
        ^
foo.cc:7:6: warning: 'i' may be used uninitialized in this function [-Wmaybe-uninitialized]
  int i,j,max;
      ^

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