3. First Number
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output

Vasya wrote down $$$n$$$ consecutive positive integers on a piece of paper. In total, there are $$$k$$$ digits written down. What number did Vasya write first?

Input

Two integers $$$n$$$ and $$$k$$$ are given, each on a separate line ($$$1 \le n \le 10^{17}$$$, $$$1 \le k \le \min(18 \cdot n, 10^{18})$$$).

Output

Output the number that was written first. If there are multiple correct answers, output the smallest one. If there are no solutions, output -1.

Examples
Input
9
10
Output
2
Input
2
1
Output
-1
Note

Grading System.

Subtask 1 (up to 28 points): $$$n \le 100$$$, $$$k \le \min(3 \cdot n, 10^3)$$$.

Subtask 2 (up to 36 points): $$$n \le 10^6$$$, $$$k \le \min(7 \cdot n, 10^7)$$$.

Subtask 3 (up to 36 points): $$$n \le 10^{17}$$$, $$$k \le \min(18 \cdot n, 10^{18})$$$.

Note: The input data and answer in the third subtask may not fit into a 32-bit integer type, it is recommended to use a 64-bit type (long long in C++, long in Java and C#, int64 in Pascal). In Python, no additional actions are required.