Problem Statement

Takahashi turned on a computer at time 0 and clicked the mouse N times. The $i-th (1 \le i \le N) click was at time T_i$.
If he consecutively clicked the mouse at time x_1 and time x_2 (where x_1 < x_2), a double click is said to be fired at time x_2 if and only if $x_2 - x_1 \le D$.
What time was a double click fired for the first time? If no double click was fired, print -1 instead.

Input

The input is given from Standard Input in the following format:
N D
$T_1 T_2 \dots T_N$

Output

If at least one double click was fired, print the time of the first such event; otherwise, print -1.

Constraints

• $1 \le N \le 100$
• $1 \le D \le 10^9$
• $1 \le T_i \le 10^9(1 \le i \le N)$
• $T_i < T_{i+1}(1 \le i \le N-1)$
• All values in the input are integers.

Sample Input 1

4 500
300 900 1300 1700

Sample Output 1

1300

Takahashi clicked the mouse at time 900 and $1300. Since 1300 - 900 \le 500, a double click was fired at time 1300$.
A double click had not been fired before time 1300, so 1300 should be printed.

Sample Input 2

5 99
100 200 300 400 500

Sample Output 2

-1

No double click was fired, so print -1.

Sample Input 3

4 500
100 600 1100 1600

Sample Output 3

600

If multiple double clicks were fired, be sure to print only the first such event.

见题面 Input 部分

见题面 Output 部分