Compilare: main.cpp: In function 'int main()': main.cpp:43:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < v.size() - 1 and !ok; i++) ~~^~~~~~~~~~~~~~ main.cpp:72:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < u.size(); i++) ~~^~~~~~~~~~ main.cpp:75:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < w.size(); i++) ~~^~~~~~~~~~ main.cpp:78:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < neutral.size(); i++) ~~^~~~~~~~~~~~~~~~