Compilare: user.cpp: In function ‘int solve(std::string)’: user.cpp:12:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s.size(); ++i) ^ user.cpp:17:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s.size(); ++i) ^ user.cpp:25:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s.size(); ++i) ^ user.cpp:34:52: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = start + 1; i < start + 1 + s.size(); ++i) ^ user.cpp:40:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s.size(); ++i) ^ /tmp/ccoHnj8D.o: In function `main': user.cpp:(.text.startup+0x80): warning: the `gets' function is dangerous and should not be used.