Contest Duration: - (local time) (100 minutes) Back to Home
A - Double Click /

Time Limit: 2 sec / Memory Limit: 1024 MB

制約

• 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)
• 入力はすべて整数

入力

N D
T_1 T_2 \dots T_N


入力例 1

4 500
300 900 1300 1700


出力例 1

1300


入力例 2

5 99
100 200 300 400 500


出力例 2

-1


入力例 3

4 500
100 600 1100 1600


出力例 3

600


Score : 100 points

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.

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.

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.

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.