D:\source\test_console-build-desktop\..\test_console\main.cpp:32: error: no matching function for call to 'accumulate(std::_Rb_tree_iterator<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, int> >, std::_Rb_tree_iterator<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, int> >, int, TestClass::sum()::Sum)'