C++ vector<vector<int>>`select only entries that appear just once -

i have vector<vector<int>> has following entries:

2 3
3 4
2 3
4 5
5 6

i need create vector<vector<int>> entries apeears once. so:

3 4
4 5
5 6

this gives result looking for. using std::map , std::pair

#include <iostream> #include <vector> #include <map>  int main() {     std::map<std::pair<int, int>, int> count_map;     std::vector<std::pair<int, int> > v;     std::vector<std::pair<int, int> > v2;     int a[10] = {2,3,3,4,2,3,4,5,5,6};      for(int = 0; < 10; i++) {         int first = a[i];         int second = a[++i];         std::pair<int, int> p = std::make_pair(first, second);         v.push_back(p);         count_map[p]++;     }      for(auto = count_map.begin(); != count_map.end(); ++it) {         if(it->second != 1) continue;         v2.push_back(it->first);         std::cout << it->first.first << ", " << it->first.second << std::endl;     } }