#include <iostream>
#include <map>
#include <vector>
#include <algorithm>
 
int main() {
	using mymap = std::map<int,int>;
 
	mymap m1 { { 1,1 }, { 2,2 }, {3,3} };
	mymap m2 { { 2,2 }, {4,4} };
 
	std::vector<mymap::value_type> diffs;
	std::set_difference( m1.begin(), m1.end(), m2.begin(), m2.end(),
	                     std::back_inserter(diffs),
	                     m1.value_comp() );
	for( auto p : diffs )	                     
	   std::cout << p.first << "-" << p.second << std::endl;
	return 0;
}

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