Compilare: user.cpp: In function ‘void read()’: user.cpp:28:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < a.size(); i++) ^ user.cpp: In function ‘void solve(int)’: user.cpp:36:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < a[x].size(); i++) ^ user.cpp: In function ‘void write()’: user.cpp:42:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < q.size(); i++) ^ user.cpp: In function ‘int main()’: user.cpp:50:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i < b.size(); i++) ^