Compilare: user.cpp: In function ‘int pair_up(int)’: user.cpp:21:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < v[node].size(); i++) ^ user.cpp:32:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < v[node].size(); i++) { ^ user.cpp: In function ‘int main()’: user.cpp:76:66: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(sir[j] >= '0' && sir[j] <= '9' && j < sir.size()) ^ user.cpp:85:66: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(sir[j] >= '0' && sir[j] <= '9' && j < sir.size()) ^