Compilare: user.cpp: In function ‘int main()’: user.cpp:28:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < s1.size(); i++) { ^ user.cpp:34:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 1; i < s2.size(); i++) { ^ user.cpp:56:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < sol.size(); i++) ^