Compilare: main.cpp: In function 'bool match(int)': main.cpp:20:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0;i < a.size();++i) ~~^~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:63:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0;i < sol.size() && i < 1000;++i) ~~^~~~~~~~~~~~