# Problem Statement
# 
# 
# 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):
    collection = [element for element in [a, b, c] if [a, b, c].count(element) == 1]
    return sum(collection)

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