Compilare: user.cpp: In function ‘void dfs(int, int)’: user.cpp:20:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<u[start].size();i++) ~^~~~~~~~~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:56:1: warning: this ‘for’ clause does not guard... [-Wmisleading-indentation] for(i=1;i<=n;i++) ^~~ user.cpp:59:5: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the ‘for’ return 0; ^~~~~~