from functools import reduce

def gcd(x, y):
 
    if x > y:
        small = y
    else:
        small = x
    for i in range(1, small+1):
        if((x % i == 0) and (y % i == 0)):
            gcd = i
             
    return gcd
 
def lcm_base(x, y):
    return (x * y) // gcd(x, y)

def lcm(*numbers):
    return reduce(lcm_base, numbers, 1)

    
def main():
    n = int(input())
    a = [int(x) for x in input().split()]

    v = lcm(*a) -1
    ans = sum(v % x for x in a)
    print(ans)
    
        
if __name__ == '__main__':
    main()
