from multiprocessing import Pool
from functools import reduce
from math import ceil

class Solver(object):
    def __init__(self):
        pass

    def solve(self):
        pass

memo = {}
def gcd(a, b):
    """a = bq + r"""
    if (a, b) not in memo:
        a, b = (max(a, b), min(a, b))
        if b == 0:
            memo[(a, b)] = a
        else:
            r = a % b
            memo[(a, b)] = gcd(b, r)
    return memo[(a, b)]

def steins_gcd(a, b) : 
    a = int(a)
    b = int(b)
  
    # GCD(0, b) == b; GCD(a, 0) == a, 
    # GCD(0, 0) == 0  
    if (a == 0) : 
        return b 
      
    if (b == 0) : 
        return a 
  
    # Finding K, where K is the  
    # greatest power of 2 that  
    # divides both a and b.  
    k = 0
      
    while(((a | b) & 1) == 0) : 
        a = a >> 1
        b = b >> 1
        k = k + 1
          
    # Dividing a by 2 until a becomes odd  
    while ((a & 1) == 0) : 
        a = a >> 1
  
    # From here on, 'a' is always odd.  
    while(b != 0) : 
          
        # If b is even, remove all  
        # factor of 2 in b  
        while ((b & 1) == 0) : 
            b = b >> 1
  
        # Now a and b are both odd. Swap if 
        # necessary so a <= b, then set  
        # b = b - a (which is even). 
        if (a > b) : 
          
            # Swap u and v. 
            a, b = b, a
  
        b = (b - a) 
      
    # restore common factors of 2  
    return int(a << k)


def lcm(a, b):
    return int((a*b) / steins_gcd(a, b))

if __name__ == "__main__":
    n = int(input())
    a_s = list(map(int, input().split(" ")))
    gcd_a = int(reduce(steins_gcd, a_s))
    lcm_a = int(reduce(lcm, a_s))
    fm = 0
    for a in a_s:
        fm += (lcm_a-1) % a
    print(fm)


### FIXED CODE ###

from functools import reduce
import math
import fractions

memo = {}
def gcd(a, b):
    """a = bq + r"""
    if (a, b) not in memo:
        a, b = (max(a, b), min(a, b))
        if b == 0:
            memo[(a, b)] = a
        else:
            r = a % b
            memo[(a, b)] = gcd(b, r)
    return memo[(a, b)]

def steins_gcd(a, b) : 
    a = int(a)
    b = int(b)
  
    # GCD(0, b) == b; GCD(a, 0) == a, 
    # GCD(0, 0) == 0  
    if (a == 0) : 
        return b 
      
    if (b == 0) : 
        return a 
  
    # Finding K, where K is the  
    # greatest power of 2 that  
    # divides both a and b.  
    k = 0
      
    while(((a | b) & 1) == 0) : 
        a = a >> 1
        b = b >> 1
        k = k + 1
          
    # Dividing a by 2 until a becomes odd  
    while ((a & 1) == 0) : 
        a = a >> 1
  
    # From here on, 'a' is always odd.  
    while(b != 0) : 
          
        # If b is even, remove all  
        # factor of 2 in b  
        while ((b & 1) == 0) : 
            b = b >> 1
  
        # Now a and b are both odd. Swap if 
        # necessary so a <= b, then set  
        # b = b - a (which is even). 
        if (a > b) : 
          
            # Swap u and v. 
            a, b = b, a
  
        b = (b - a) 
      
    # restore common factors of 2  
    return int(a << k)

def another_gcd(x, y):
    while y != 0:
        (x, y) = (y, x % y)
    return x


def lcm(a, b):
    return abs(a*b) // fractions.gcd(a, b)

if __name__ == "__main__":
    n = int(input())
    a_s = list(map(int, input().split(" ")))

    lcm_a = int(reduce(lcm, a_s))

    fm = 0
    for a in a_s:
        fm += (lcm_a-1) % a
    print(fm)