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 Rust (judge verdict: Accepted)

use std::io;

fn main() {
    let mut tmp_str = String::new();
    // 標準入力から一行受け取る
    io::stdin().read_line( &mut tmp_str );

    // 標準入力から受け取った文字を数字に変換する
    let linenum: i32 = tmp_str.trim().parse().expect( "expected val is inreger" );

    // 動的配列を宣言
    let mut numv: Vec<i32> = Vec::new();
    for i in 0..linenum {
        // enter区切りで標準入力から数値を受け取り, 動的配列の末尾へpushする
        tmp_str = String::new();
        io::stdin().read_line( &mut tmp_str );
        let tmp_val = tmp_str.trim().parse().expect( "Failed read line from standard input" );
        numv.push( tmp_val );
    }

    let mut max_val = -1000000000;
    let mut min_val = numv[0];
    for i in 1..linenum {
        if max_val < numv[i as usize] - min_val {
            max_val = numv[i as usize] - min_val;
        }

        if min_val > numv[i as usize] {
            min_val = numv[i as usize];
        }
    }
    println!( "{}", max_val );
}