How can I press enter to exit. And if no input to prompt the "There must be at least one player!" message?

Question

print("Player name or <ENTER> to end:", end="")
if(players == 0):
player1 = input()
if(player1 == ""):
print("There must be at least one player!")
if(player1 == ""):
exit()
else:
players += 1

Answer 1

It's impossible, to read input you must press enter. And if you already have another idea for blank input. How would you exit by enter?