Compilare: user.cpp: In function ‘void cer_b()’: user.cpp:155:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0, a, b; i<sol.size(); ++i) ^ user.cpp: In function ‘void cer_a()’: user.cpp:129:23: warning: ‘yf’ may be used uninitialized in this function [-Wmaybe-uninitialized] g << xf << ' ' << yf << ' ' << dist-1 << '\n'; ^ user.cpp:129:10: warning: ‘xf’ may be used uninitialized in this function [-Wmaybe-uninitialized] g << xf << ' ' << yf << ' ' << dist-1 << '\n'; ^