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: Accepted)

fn main() {
    let buf = io::read_string();
    let mut sc = io::Scanner::new(&buf);
    let n: usize = sc.read();
    let a: Vec<usize> = sc.read_vec(n);

    let mut res = 0;
    for i in 0..n {
        res += a[i] - 1;
    }
    println!("{}", res);
}

#[allow(dead_code)]
mod io {
    use std;
    use std::io::Read;
    use std::str::{FromStr, SplitWhitespace};
    pub struct Scanner<'a> {
        pub iter: SplitWhitespace<'a>,
    }
    impl<'a> Scanner<'a> {
        pub fn new(s: &'a str) -> Scanner<'a> {
            Scanner {
                iter: s.split_whitespace(),
            }
        }
        pub fn read<T: FromStr>(&mut self) -> T {
            self.iter
                .next()
                .unwrap()
                .parse()
                .ok()
                .expect("parsing failed")
        }
        pub fn read_vec<T: FromStr>(&mut self, n: usize) -> Vec<T> {
            (0..n).map(|_| self.read()).collect()
        }
    }
    pub fn read_string() -> String {
        let mut s = String::new();
        std::io::stdin().read_to_string(&mut s).unwrap();
        s
    }
}