Alternative moves
Problem
You are given three integers N, A, and B. You have another integer X = 0. You can apply the following move (1-indexed) any number of times:
- During the odd-numbered moves(1, 3, 5,....), you have to set X = X + A.
- During the even-numbered moves(2, 4, 6,....), you have to set X = X - B.
Find the minimum number of moves required so that the value of X becomes greater than or equal to N or print -1 if it is impossible to do so.
Input format
- The first line contains T denoting the number of test cases. The description of T test cases is as follows:
- Each test case consists of a single line containing three integers N, A, and B.
Output format
For each test case, print the minimum number of moves required so that the value of X becomes greater than or equal to N or print -1 otherwise.
Constraints
1≤T≤1051≤N,A,B≤109
Time Limit: 1
Memory Limit: 256
Source Limit:
Explanation
The first test case
- During the first move you set X = 0 + 5 = 5 >= N = 5. Hence only one move is required.
The second test case
- It is impossible to make X >= N by applying the given move any number of times.
The third test case
- During the first move you set X = 0 + 4 = 4.
- During the second move you set X = 4 - 1 = 3.
- During the third move you set X = 3 + 4 = 7 >= N = 6. Hence minimum three moves are required.
