print("Login : ");
login = in.readLine();
print("Password: ");
password = in.readLine();
UserManagerAdmin uma = (UserManagerAdmin)Naming.lookup(rmiURL);
while ((userManager = uma.login(login, password)) == null) {
println("login failed!\n");
print("Login : ");
login = in.readLine();
print("Password: ");
password = in.readLine();