Compilare: user.cpp: In function ‘void solve()’: user.cpp:66:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i <= d.size(); ++i) { ~~^~~~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:85:10: warning: unused variable ‘cin_buff’ [-Wunused-variable] auto cin_buff = cin.rdbuf(); ^~~~~~~~ user.cpp:86:10: warning: unused variable ‘cout_buff’ [-Wunused-variable] auto cout_buff = cout.rdbuf(); ^~~~~~~~~