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 Go (judge verdict: Accepted)

package main

import (
        "bufio"
        "fmt"
        "os"
        "strconv"
)

var sc = NewScanner()

func main() {
        n := sc.NextInt()
        minr := sc.NextInt()

        var (
                r   int
                max = int(-1*2e10 - 1)
        )
        for i := 1; i < n; i++ {
                r = sc.NextInt()
                diff := r - minr
                if max < diff {
                        max = diff
                }
                if minr > r {
                        minr = r
                }
        }
        fmt.Println(max)
}

type Scanner struct {
        sc *bufio.Scanner
}

func NewScanner() *Scanner {
        sc := bufio.NewScanner(os.Stdin)
        sc.Split(bufio.ScanWords)
        return &Scanner{sc}
}

func (sc *Scanner) NextInt() int {
        sc.sc.Scan()
        i, err := strconv.Atoi(sc.sc.Text())
        if err != nil {
                panic(err)
        }
        return i
}