Problem:
MathJax.Hub.Config({ tex2jax: { inlineMath: [["$","$"], ["\\(","\\)"]], processEscapes: true }});

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

func max(x, y int) int {
	if x < y {
		return y
	} else {
		return x
	}
}

func min(x, y int) int {
	if x < y {
		return x
	} else {
		return y
	}
}
func main() {
	scanner := bufio.NewScanner(os.Stdin)
	var n int
	scanner.Scan()
	n, _ = strconv.Atoi(scanner.Text())
	rate := make([]int, n)
	for i := range rate {
		scanner.Scan()
		rate[i], _ = strconv.Atoi(scanner.Text())
	}
	minRate := rate[0]
	maxValue := 1 - 10*10*10*10*10*10*10*10*10 - 1

	for i := 1; i < n; i++ {
		maxValue = max(maxValue, rate[i] - minRate)
		minRate = min(minRate, rate[i])
	}

	fmt.Println(maxValue)
}