Compilare: main.cpp: In function 'int main()': main.cpp:36:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<elem.size() && elem[j].first<M_PI;j++) ~^~~~~~~~~~~~ main.cpp:39:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(;it<elem.size() && elem[it].first-elem[j].first<M_PI;it++)counter+=elem[it].second; ~~^~~~~~~~~~~~