Compilare: user.cpp: In function ‘void dfs(int, int)’: user.cpp:17:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < L[in].size(); i ++) { ^ user.cpp: In function ‘int main()’: user.cpp:102:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < ret.size(); i ++) { ^ user.cpp:106:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 1; j < ret[i].size(); j ++) { ^