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

var sc = bufio.NewScanner(os.Stdin)

func scanInt() int {
	sc.Scan()
	num, e := strconv.Atoi(sc.Text())
	if e != nil {
		log.Fatal(e)
	}
	return num
}

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

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

func main() {
	N := scanInt()
	maxv := -1000000000
	minv := scanInt()
	for i := 0; i < N-1; i++ {
		r := scanInt()
		maxv = max(maxv, r-minv)
		minv = min(minv, r)
	}
	fmt.Println(maxv)
}