Compilare: main.cpp: In function 'int main()': main.cpp:62:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<ub.size();i++) ~^~~~~~~~~~ main.cpp:63:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<ub.size();j++) ~^~~~~~~~~~ main.cpp:65:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<ub.size();i++) ~^~~~~~~~~~