#include <iostream>
struct range{
  struct iterator{
    int i;
    int operator*() const {return i;}
    iterator& operator++() {++i;return *this;}
    bool operator!=(iterator const& rhs) const{return i!=rhs.i;}
  };
  int b;
  int e;
  explicit range(int e):range(0,e){}
  range(int b,int e):b{b},e{e}{}
  iterator begin() const{return {b};}
  iterator end() const {return {e};}
};
 
int main()
{  
  for(int i:range(10)) {
    std::cout<<i<<std::endl;
  }
}
 
 

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