Compilare: user.cpp: In function ‘void bfs(int)’: user.cpp:20:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<=a[x].size()-1;i++) ^ user.cpp:35:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<=a[x].size()-1;i++) ^ user.cpp: In function ‘int main()’: user.cpp:82:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j=0;j<=l[i].size()-1;j++) ^