Compilare: main.cpp: In function 'void dfs(int, int)': main.cpp:46:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<a[x].size(); ++i) ~^~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:55:11: warning: unused variable 'x' [-Wunused-variable] int i,x,y; ^ main.cpp:55:13: warning: unused variable 'y' [-Wunused-variable] int i,x,y; ^