#include <bits/stdc++.h>
using namespace std;
int gcd(long long int x, long long int y) { return y == 0 ? x : gcd(y, x % y); }
int lcm(long long int x, long long int y) { return x * y / gcd(x, y); }
int main() {
  int n;
  cin >> n;
  vector<int> a(n);
  for (long long int i = 0; i < n; i++) {
    cin >> a[i];
  }
  int A = a[0];
  for (long long int i = 0; i < n; i++) {
    A = lcm(A, a[i]);
  }
  A--;
  int f = 0;
  for (long long int i = 0; i < n; i++) {
    f += A % a[i];
  }
  cout << f << endl;
  return 0;
}
