Compilare: main.cpp: In function 'int main()': main.cpp:24:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < b.size(); i++) { ~~^~~~~~~~~~ main.cpp:32:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 1; j < c.size(); j++) { ~~^~~~~~~~~~