Compilare: main.cpp: In function 'int main()': main.cpp:37:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < lista[x].size(); i++) ~~^~~~~~~~~~~~~~~~~ main.cpp:61:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < lista[y].size() && ok < 0; j++) ~~^~~~~~~~~~~~~~~~~