t = int(input())
sum1 = 0
sum2 = 0
for i in range(t):
a, b, k = map(int, input().split())
sum1 = int(a * (k // 2))
sum2 = int(b * (k // 2))
if k % 2 == 1:
sum1 = sum1 + a
print(sum1 - sum2)
sum1 = 0
sum2 = 094. Binary Tree Inorder Traversal | 101. Symmetric Tree |
77. Combinations | 46. Permutations |
226. Invert Binary Tree | 112. Path Sum |
1556A - A Variety of Operations | 136. Single Number |
169. Majority Element | 119. Pascal's Triangle II |
409. Longest Palindrome | 1574A - Regular Bracket Sequences |
1574B - Combinatorics Homework | 1567A - Domino Disaster |
1593A - Elections | 1607A - Linear Keyboard |
EQUALCOIN Equal Coins | XOREQN Xor Equation |
MAKEPAL Weird Palindrome Making | HILLSEQ Hill Sequence |
MAXBRIDGE Maximise the bridges | WLDRPL Wildcard Replacement |
1221. Split a String in Balanced Strings | 1002. Find Common Characters |
1602A - Two Subsequences | 1555A - PizzaForces |
1607B - Odd Grasshopper | 1084A - The Fair Nut and Elevator |
1440B - Sum of Medians | 1032A - Kitchen Utensils |