2026 年 USACO竞赛 首场比赛铜奖组问题一—Chip Exchange

Bessie the cow has in her possession A chips of type A and B chips of type B (0≤A,B≤109). She can perform the following operation as many times as she likes:

If you have at least cB chips of type B, exchange cB chips of type B for cA chips of type A (1≤cA ,cB≤109).

Determine the minimum non-negative integer x such that the following holds: after receiving x additional random chips, it is guaranteed that Bessie can end up with at least fA chips of type A (0≤fA≤109).

INPUT FORMAT (input arrives from the terminal / stdin):

The first line contains T, the number of independent test cases (1≤T≤104).

Then follow T tests, each consisting of five integers A,B,cA,cB,fA.

OUTPUT FORMAT (print output to the terminal / stdout):

Output the answer for each test on a separate line.

Note: The large size of integers involved in this problem may require the use of 64-bit integer data types (e.g., a "long long" in C/C++).

SAMPLE INPUT:

2
2 3 1 1 6
2 3 1 1 4

SAMPLE OUTPUT:

1
0

SAMPLE INPUT:

5
0 0 2 3 5
0 1 2 3 5
1 0 2 3 5
10 10 2 3 5
0 0 1 1000000000 1000000000

SAMPLE OUTPUT:

9
8
7
0
1000000000000000000

For the first test, Bessie initially starts with no chips. If she receives any 9 additional chips, she can perform the operation to end up with at least 5 chips of type A. For example, if she receives 2 chips of type A and 7 chips of type B, she can perform the operation twice to end up with 6≥5 chips of type A. However, if she only receive 8 chips of type B, she can only end up with 4<5 chips of type A.

For the fourth test, she already has enough chips of type A from the start.

SCORING:

Input 3: cA=cB=1
Inputs 4-5: x ≤10 for all cases
Inputs 6-7: cA=2, cB=3
Inputs 8-12: No additional constraints.

Problem credits: Benjamin Qi