Problem:
Score : 400 points

Problem Statement

One day, Snuke was given a permutation of length N, a_1, a_2, ..., a_N, from his friend.

Find the following:

Constraints

1 ≦ N ≦ 200,000

(a_1, a_2, ..., a_N) is a permutation of (1, 2, ..., N).

Input

The input is given from Standard Input in the following format:

N
a_1 a_2 ... a_N

Output

Print the answer.

Note that the answer may not fit into a 32-bit integer.

Sample Input 1

3
2 1 3

Sample Output 1

9

Sample Input 2

4
1 3 2 4

Sample Output 2

19

Sample Input 3

8
5 4 8 1 2 6 7 3

Sample Output 3

85

Solution in Rust (1.15.1) (judge verdict: Wrong Answer)

fn main() {
  let _: usize = read();
  let vec: &Vec<i64> = &read_vec();
  
  let csum = vec.iter().scan(0,|a,&x|{*a+=x; Some(*a)}).sum::<i64>();
  
  let mut buf = vec![];
  let mut cd = 0;
  let mut amax = vec[0];
  for &a in vec {
    let d = std::cmp::max(0, amax - a);
    cd += d;
    buf.push(cd);
    amax = std::cmp::max(amax, a);
  }
  let cdiff = buf.iter().sum::<i64>();
  
  println!("{}", csum - cdiff);
}

fn read<T: std::str::FromStr>() -> T {
  let mut buf = String::new();
  std::io::stdin().read_line(&mut buf).ok();
  buf.trim().parse::<T>().ok().unwrap()
}

fn read_vec<T: std::str::FromStr>() -> Vec<T> {
  let mut buf = String::new();
  std::io::stdin().read_line(&mut buf).ok();
  buf.trim().split_whitespace().map(|t| t.parse::<T>().ok().unwrap()).collect()
}