Compilare: user.cpp: In function ‘void makeprefix()’: user.cpp:10:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 1; i < A.size(); i++) ^ user.cpp: In function ‘int main()’: user.cpp:26:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 1; i < B.size(); i++) ^ user.cpp:32:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (k == A.size() - 1) ^