Maximum Profit

You can obtain profits from foreign exchange margin transactions. For example, if you buy 1000 dollar at a rate of 100 yen per dollar, and sell them at a rate of 108 yen per dollar, you can obtain (108 - 100) × 1000 = 8000 yen.

Write a program which reads values of a currency $R_t$ at a certain time $t$ ($t = 0, 1, 2, ... n-1$), and reports the maximum value of $R_j - R_i$ where $j > i$ .

Constraints

• $2 \leq n \leq 200,000$
• $1 \leq R_t \leq 10^9$

Input

The first line contains an integer $n$. In the following $n$ lines, $R_t$ ($t = 0, 1, 2, ... n-1$) are given in order.

Output

Print the maximum value in a line.

Examples

Input

6 5 3 1 3 4 3

Output

3

Input

3 4 3 2

Output

-1

inputFormat

Input

The first line contains an integer $n$. In the following $n$ lines, $R_t$ ($t = 0, 1, 2, ... n-1$) are given in order.

outputFormat

Output

Print the maximum value in a line.

Examples

Input

6 5 3 1 3 4 3

Output

3

Input

3 4 3 2

Output

-1

样例

3
4
3
2

-1