#include <list>
#include <map>
#include <set>
#include <string>
#include <iostream>
 
int main()
{
    std::list<std::map<std::set<std::string>, int>> l =
    {
      {
        {{"a"}, 0},
        {{"b"}, 1},
        {{"c"}, 2},
      },{
        {{"a", "b"}, 3},
        {{"a", "c"}, 4},
        {{"b", "c"}, 5}
      },{
        {{"a", "b", "c"}, 6},
      }
    };
 
    for(auto list_it = l.begin(); list_it != l.end(); ++list_it)
        for(auto map_it = list_it->begin(); map_it != list_it->end(); ++map_it)
            std::cout << map_it->second << ' ';
    std::cout << '\n';
}
 

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