#include <iostream>
#include <map>
#include <set>
using namespace std;
 
struct ZZ{};
 
int main() {
 
 
	map<ZZ, std::set<ZZ>> mapa;  
	std::map<ZZ, std::set<ZZ>>::iterator it_map;  
	std::set<ZZ>::iterator it_set1, it_set2;    
 
	for(it_map = mapa.begin(); it_map != mapa.end(); ++it_map){     
	    for(it_set1 = it_map->second.begin(); it_set1 != it_map->second.end(); ++it_set1){
	        for(it_set2 = ++it_set1; it_set2 != it_map->second.end(); ++it_set2){
	        /*
	        some function which use *it_set1, *it_set2
	        */
	        }
	    }
	}
 
	return 0;
}

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