Compilare: user.cpp: In function ‘int main()’: user.cpp:49:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < normalization.size(); ++i) { ~~^~~~~~~~~~~~~~~~~~~~~~ user.cpp:50:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i + 1 < normalization.size() and normalization[i].first < normalization[i + 1].first) { ~~~~~~^~~~~~~~~~~~~~~~~~~~~~