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"
	"math"
	"os"
	"strconv"
)

func main() {
	sc := bufio.NewScanner(os.Stdin)
	n := stdin(sc)
	ary := make([]int, n)
	for i := 0; i < n; i++ {
		v := stdin(sc)
		ary[i] = v
	}
	maxv := -math.MaxInt32
	minv := ary[0]
	for i := 1; i < n; i++ {
		maxv = max(maxv, ary[i]-minv)
		minv = min(minv, ary[i])
	}
	fmt.Println(maxv)
}

func stdin(sc *bufio.Scanner) int {
	sc.Scan()
	num, _ := strconv.Atoi(sc.Text())
	return num
}

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}

func max(a, b int) int {
	if a < b {
		return b
	}
	return a
}