Compilare: user.cpp: In function ‘int main()’: user.cpp:34:46: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int u = 0; u <= v1.size() - 1; ++u) ^ user.cpp:36:46: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int u = 0; u <= v2.size() - 1; ++u) ^ user.cpp:40:46: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int u = 0; u <= v1.size() - 1; ++u) ^ user.cpp:42:46: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int u = 0; u <= v2.size() - 1; ++u) ^ user.cpp:46:46: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int u = 0; u <= v1.size() - 1; ++u) ^ user.cpp:48:46: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int u = 0; u <= v2.size() - 1; ++u) ^ user.cpp:75:22: warning: ‘t’ may be used uninitialized in this function [-Wmaybe-uninitialized] fout << t; ^ user.cpp:73:22: warning: ‘j’ may be used uninitialized in this function [-Wmaybe-uninitialized] fout << j; ^