A14218. Education

Polycarp is wondering about buying a new computer, which costs $c$ tugriks. To do this, he wants to get a job as a programmer in a big company.

There are $n$ positions in Polycarp's company, numbered starting from one. An employee in position $i$ earns $a[i]$ tugriks every day. The higher the position number, the more tugriks the employee receives. Initially, Polycarp gets a position with the number $1$ and has $0$ tugriks.

Each day Polycarp can do one of two things:

- If Polycarp is in the position of $x$ , then he can earn $a[x]$ tugriks.
- If Polycarp is in the position of $x$ ( $x < n$ ) and has at least $b[x]$ tugriks, then he can spend $b[x]$ tugriks on an online course and move to the position $x+1$ .

For example, if $n=4$ , $c=15$ , $a=[1, 3, 10, 11]$ , $b=[1, 2, 7]$ , then Polycarp can act like this:

- On the first day, Polycarp is in the $1$ -st position and earns $1$ tugrik. Now he has $1$ tugrik;
- On the second day, Polycarp is in the $1$ -st position and move to the $2$ -nd position. Now he has $0$ tugriks;
- On the third day, Polycarp is in the $2$ -nd position and earns $3$ tugriks. Now he has $3$ tugriks;
- On the fourth day, Polycarp is in the $2$ -nd position and is transferred to the $3$ -rd position. Now he has $1$ tugriks;
- On the fifth day, Polycarp is in the $3$ -rd position and earns $10$ tugriks. Now he has $11$ tugriks;
- On the sixth day, Polycarp is in the $3$ -rd position and earns $10$ tugriks. Now he has $21$ tugriks;
- Six days later, Polycarp can buy himself a new computer.

Find the minimum number of days after which Polycarp will be able to buy himself a new computer.

The first line contains a single integer $t$ ( $1 \le t \le 10^4$ ). Then $t$ test cases follow.

The first line of each test case contains two integers $n$ and $c$ ( $2 \le n \le 2 \cdot 10^5$ , $1 \le c \le 10^9$ ) — the number of positions in the company and the cost of a new computer.

The second line of each test case contains $n$ integers $a_1 \le a_2 \le \ldots \le a_n$ ( $1 \le a_i \le 10^9$ ).

The third line of each test case contains $n - 1$ integer $b_1, b_2, \ldots, b_{n-1}$ ( $1 \le b_i \le 10^9$ ).

It is guaranteed that the sum of $n$ over all test cases does not exceed $2 \cdot 10^5$ .

For each test case, output the minimum number of days after which Polycarp will be able to buy a new computer.