Compilare: user.cpp: In function ‘void DFS(int)’: user.cpp:34:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<a[k].size(); i++) ^ user.cpp: In function ‘void Euler()’: user.cpp:73:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0; j<a[i].size() && a[i][j]!=k; j++) ; ^ user.cpp: In function ‘int main()’: user.cpp:98:16: warning: unused variable ‘i’ [-Wunused-variable] int i; ^