Compilare: user.cpp: In function ‘int main()’: user.cpp:13:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i <G[0].size(); ++i) ~~^~~~~~~~~~~~ user.cpp:17:9: warning: variable ‘x’ set but not used [-Wunused-but-set-variable] int x = big; ^