checker.cpp: In function 'int main()':
checker.cpp:21:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
21 | for (int i = 1; i < vec.size(); i ++){
| ~~^~~~~~~~~~~~
checker.cpp:22:20: error: '__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> >, std::vector<int> >::value_type' {aka 'class std::vector<int>'} has no member named 'first'
22 | if (vec[i].first >= vec[i - 1].second) continue;
| ^~~~~
checker.cpp:22:40: error: '__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> >, std::vector<int> >::value_type' {aka 'class std::vector<int>'} has no member named 'second'
22 | if (vec[i].first >= vec[i - 1].second) continue;
| ^~~~~~
checker.cpp:23:20: error: '__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> >, std::vector<int> >::value_type' {aka 'class std::vector<int>'} has no member named 'second'
23 | if (vec[i].second <= vec[i - 1].second) continue;
| ^~~~~~
checker.cpp:23:41: error: '__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> >, std::vector<int> >::value_type' {aka 'class std::vector<int>'} has no member named 'second'
23 | if (vec[i].second <= vec[i - 1].second) continue;
| ^~~~~~