Compilare: main.cpp: In function 'int main()': main.cpp:102:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int k = 0; k < input.size(); k++) ~~^~~~~~~~~~~~~~ main.cpp:136:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < elem.size() - 1; i++) ~~^~~~~~~~~~~~~~~~~ main.cpp:147:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < sol.size(); i++) ~~^~~~~~~~~~~~