foo.cc: In function 'int main()':
foo.cc:12:25: error: no 'operator++(int)' declared for postfix '++' [-fpermissive]
   12 |                 ma[a[i]]++;
      |                 ~~~~~~~~^~
foo.cc:15:40: error: no match for 'operator[]' (operand types are 'std::vector<int> [5000099]' and 'std::unordered_map<int, int>')
   15 |         for(int i=1;i<=(int)5e4;++i) ve[ma[a[i]]].push_back(a[i]);
      |                                        ^

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