foo.cc: In function 'int main()':
foo.cc:40:13: warning: unused variable 'ma' [-Wunused-variable]
   40 |         int ma = 0;
      |             ^~
foo.cc:47:13: warning: unused variable 'len' [-Wunused-variable]
   47 |         int len = unique(V.begin(), V.end()) - V.begin();
      |             ^~~

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