foo.cc:4: warning: ignoring #pragma gcc optimize [-Wunknown-pragmas]
    4 | #pragma gcc optimize(2)
      | 
foo.cc: In function 'int main()':
foo.cc:45:2: error: 'maxn' was not declared in this scope; did you mean 'main'?
   45 |  maxn=1;
      |  ^~~~
      |  main
foo.cc:49:6: warning: unused variable 'sc' [-Wunused-variable]
   49 |  int sc=1<<bits;
      |      ^~

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