Compilare: user.cpp: In function ‘void tarjan(int)’: user.cpp:20:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < l[x].size(); ++i) ~~^~~~~~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:57:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < ctc.size(); ++i) { ~~^~~~~~~~~~~~ user.cpp:58:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < ctc[i].size(); ++j) ~~^~~~~~~~~~~~~~~