才开始准备先减较小的数，但是好像没有考虑到范围的限制，WA 了😡

直接取暴力两种情况最小值，AC

t = int(input())
for _ in range(t):
    a, b, x, y, n = map(int, input().split())
    a_ = min(a - x, n)
    a1 = a - a_
    remain = n - a_
    b1_ = min(b - y, remain)
    b1 = b - b1_
  
    b_ = min(b - y, n)
    b2 = b - b_
    remain = n - b_
    a2_ = min(a - x, remain)
    a2 = a - a2_
  
    print(min(a1 * b1, a2 * b2))