Compilare: main.cpp: In instantiation of '<lambda(auto:2&&)> [with auto:2 = std::vector<std::vector<int> >&]': main.cpp:58:32: required from here main.cpp:29:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (auto i = 0; i < n; ++i) ~~^~~ main.cpp:32:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (auto j = i; j < n; ++j) ~~^~~ main.cpp:34:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (auto k = 0; k < n; ++k) ~~^~~