Compilare: main.cpp: In function 'void DFS(int)': main.cpp:14:15: warning: unused variable 'it' [-Wunused-variable] for (auto it : a[node]) ^~ main.cpp: In function 'int main()': main.cpp:27:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (size_t i = 0; i < m; i++) ~~^~~ main.cpp:37:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (size_t i = 1; i <= n; i++) { ~~^~~~ main.cpp:24:9: warning: unused variable 'first_node' [-Wunused-variable] int first_node, n, m; ^~~~~~~~~~