# find the maximum score 
sentinel = -999 # an unexpected score value 
maximum = sentinel # signifies that maximum is not yet set 

while True: 
  print("Enter a score [", sentinel, "to exit]: ") 
  aScore = int(input()) # see 5.1
  if aScore == sentinel: break # that's the signal to exit this loop  
  if maximum == sentinel or maximum < aScore: maximum = aScore

# find the minimum score 
sentinel = -999 # an unexpected score value 
minimum = sentinel # signifies that maximum is not yet set 

while True: 
  print("Enter a score [", sentinel, "to exit]: ") 
  aScore = int(input()) # see 5.1
  if aScore == sentinel: break # that's the signal to exit this loop  
  if minimum == sentinel or minimum > aScore: minimum = aScore
 
# find the maximum and minimum scores 
sentinel = -999 # an unexpected score value 
maximum  = sentinel # signifies that maximum is not yet set 
minimum = sentinel # signifies that maximum is not yet set 

while True: 
  print("Enter a score [", sentinel, "to exit]: ") 
  aScore = int(input()) # see 5.1
  if aScore == sentinel: break # that's the signal to exit this loop  
  if maximum == sentinel or maximum < aScore: maximum = aScore
  if minimum == sentinel or minimum > aScore: minimum = aScore