Problem:
Score : 300 points

Problem Statement

You are given N positive integers a_1, a_2, ..., a_N.

For a non-negative integer m, let f(m) = (m\ mod\ a_1) + (m\ mod\ a_2) + ... + (m\ mod\ a_N).

Here, X\ mod\ Y denotes the remainder of the division of X by Y.

Find the maximum value of f.

Constraints

All values in input are integers.

2 \leq N \leq 3000

2 \leq a_i \leq 10^5

Input

Input is given from Standard Input in the following format:

N
a_1 a_2 ... a_N

Output

Print the maximum value of f.

Sample Input 1

3
3 4 6

Sample Output 1

10

f(11) = (11\ mod\ 3) + (11\ mod\ 4) + (11\ mod\ 6) = 10 is the maximum value of f.

Sample Input 2

5
7 46 11 20 11

Sample Output 2

90

Sample Input 3

7
994 518 941 851 647 2 581

Sample Output 3

4527

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


use std::io::*;
use std::str::FromStr;

pub fn read<T: FromStr>() -> T {
  let stdin = stdin();
  let stdin = stdin.lock();
  let token: String = stdin
    .bytes()
    .map(|c| c.expect("failed to read char") as char)
    .skip_while(|c| c.is_whitespace())
    .take_while(|c| !c.is_whitespace())
    .collect();
  token.parse().ok().expect("failed to parse token")
}

use std::cmp::{max, min};

fn main() {
  let n = read::<i32>();
  let mut a = vec![];

  for _ in 0..n {
    let ai = read::<i32>();
    a.push(ai);
  }

  let mut a_lcm = 1;

  for i in &a {
    a_lcm = lcm(a_lcm, *i as usize);
  }
  // println!("{}", a_lcm);
  let ans: i32 = a.iter().map(|x| (a_lcm - 1) as i32 % *x).sum();
  println!("{}", ans)

}

fn gcd(a: usize, b: usize) -> usize {
  if a % b == 0 {
    b
  } else {
    gcd(b, a % b)
  }
}

fn lcm(a: usize, b: usize) -> usize {
  a * b / gcd(a, b)
}