Compilare: user.cpp: In function ‘void solve(int)’: user.cpp:31:35: 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:37:32: 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:45:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i < b.size(); i++) ^