Compilare: main.cpp: In function 'int main()': main.cpp:30:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < a.size(); i++){ ~~^~~~~~~~~~ main.cpp:35:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < a.size(); i++){ ~~^~~~~~~~~~ main.cpp:41:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < a.size(); i++){ ~~^~~~~~~~~~ main.cpp:48:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = a.size(); i < b.size(); i++){ ~~^~~~~~~~~~