import core.bitop;
import std.algorithm;
import std.ascii;
import std.bigint;
import std.conv;
import std.functional;
import std.math;
import std.numeric;
import std.range;
import std.stdio;
import std.string;
import std.random;
import std.typecons;
import std.container;

alias sread = () => readln.chomp();
ulong MOD = 1_000_000_007;
ulong INF = 1_000_000_000_000;
alias Score = Tuple!(long, "p", long, "c");

T lread(T = long)()
{
    return readln.chomp.to!T();
}

T[] aryread(T = long)()
{
    return readln.split.to!(T[])();
}

void scan(TList...)(ref TList Args)
{
    auto line = readln.split();
    foreach (i, T; TList)
    {
        T val = line[i].to!(T);
        Args[i] = val;
    }
}

void main()
{
    auto n = readln.chomp.to!(double);
    auto a = readln.split.to!(double[]);
    auto l = a.lcm();
    double f = 0;
    foreach (e; a)
        f += (l - 1) % e;
    f.to!(int).writeln();
}

auto lcm(T)(T a)
{
    double ret = a[0];
    foreach(e; a[1 .. $])
    {
        double tmp = gcd(ret, e);
        ret = ret * e / tmp;
    }
    return ret;
}