use std::io::stdin;
use std::str::FromStr;
#[allow(dead_code, unused_mut)]
fn read<T: FromStr>() -> T {
    let mut s = String::new();
    stdin().read_line(&mut s).ok();
    s.trim().parse().ok().expect("1")
}
#[allow(dead_code, unused_mut)]
fn read_vec<T: FromStr>() -> Vec<T> {
    read::<String>()
        .split_whitespace()
        .map(|e| e.parse().ok().expect("2"))
        .collect()
}
#[allow(dead_code, unused_mut)]
fn read_two<T: FromStr>() -> (T, T) {
    let mut s = String::new();
    stdin().read_line(&mut s).unwrap();
    let mut x = s.split_whitespace().map(|x| x.parse().ok().unwrap());
    (x.next().unwrap(), x.next().unwrap())
}
#[allow(dead_code, unused_mut)]
fn read_three<T: FromStr>() -> (T, T, T) {
    let mut s = String::new();
    stdin().read_line(&mut s).unwrap();
    let mut x = s.split_whitespace().map(|x| x.parse().ok().unwrap());
    (x.next().unwrap(), x.next().unwrap(), x.next().unwrap())
}
#[allow(dead_code)]
fn remove_whitespace(s: &str) -> String {
    s.chars().filter(|c| !c.is_whitespace()).collect()
}

#[allow(unused_imports)]
use std::io::{stdout, Write};
#[allow(unused_imports)]
use std::collections::HashMap;
fn gcd(mut x: u64, mut y: u64) -> u64 {
    let mut z = x;
    let mut gcd_num = x;
    while z != 0 {
        gcd_num = z;
        z = y % x;
        y = x;
        x = z;
    }
    gcd_num
}
fn main() {
    let n: usize = read();
    let mut v: Vec<u64> = read_vec();
    v.sort();
    let mut num = v[0] * v[1] / gcd(v[0], v[1]);
    for i in 2..n {
         num = num * v[i] / gcd(num, v[i]);
    }
    num -= 1;
    let mut ans = 0;
    for i in v {
        ans += num % i;
    }
    println!("{}", ans);
}
