Compilare: main.cpp: In function 'int main()': main.cpp:43:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(p.at(key).size() > maxlen) maxlen = p.at(key).size(); ~~~~~~~~~~~~~~~~~^~~~~~~~ main.cpp:55:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(element.second.size() == maxlen) ~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~ main.cpp:63:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < p.at(example).size(); i++) ~~^~~~~~~~~~~~~~~~~~~~~~