Compilare: user.cpp: In function ‘void read()’: user.cpp:35:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i< a.size(); i++) ^ user.cpp: In function ‘void solve()’: user.cpp:49:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<q.size(); i++) ^ user.cpp:51:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=0; j<a[q[i]].size(); j++) ^ user.cpp: At global scope: user.cpp:68:6: warning: ISO C++ forbids declaration of ‘main’ with no type [-Wreturn-type] main() ^