Problem:
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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 $j > i$ .

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.

Constraints

$2 \leq n \leq 200,000$

$1 \leq R_t \leq 10^9$

Sample Input 1

6
5
3
1
3
4
3

Sample Output 1

3

Sample Input 2

3
4
3
2

Sample Output 2

-1

Solution in Scala (judge verdict: Accepted)

import scala.io.StdIn.readInt

object Main {
   def main(args: Array[String]) = {
     val n = readInt()
     val r0 = readInt()
     val r1 = readInt()
     var max = r1 - r0
     var min = if(r0 > r1) r1 else r0

     for( i <- 2 to n-1 ) {
       val m = readInt()
       if( max < m - min) {
         max = m - min
         if( min > m )
           min = m
       }
       else if( min > m ) {
         min = m
       }
     }
     println(max)
  }
}