import java.util.*;

class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    int a[] = new int[N];
    int m = 1;
    for (int i = 0; i < N; i++) {
      a[i] = sc.nextInt();
      m *= a[i];
    }
    int ans = 0;
    for (int i = 0; i < N; i++) {
      ans += (m - 1) % a[i];
    }
    System.out.println(ans);
  }
}