<gh_stars>1-10
# Given 3 int values, a b c, return their sum. However, if one of the values is
# the same as another of the values, it does not count towards the sum. 

# lone_sum(1, 2, 3) --> 6
# lone_sum(3, 2, 3) --> 2
# lone_sum(3, 3, 3) --> 0

def lone_sum(a, b, c):
  sum = 0
  
  if (a != b and a != c): sum += a
  if (b != a and b != c): sum += b
  if (c != a and c != b): sum += c
  
  return sum

print(lone_sum(1, 2, 3))
print(lone_sum(3, 2, 3))
print(lone_sum(3, 3, 3))
