#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;

int main() {
  int n;
  cin >> n;
  vector<long long> a(n);
  for(int i = 0; i < n; i++){
    cin >> a[i];
  }

  long long LCM = a[0];
  for(int i = 1; i < n; i++){
    LCM = LCM * a[i] / __gcd(LCM, a[i]);
  }

  long long sum = 0;
  for(int i = 0; i < n; i++){
    sum += (LCM - 1) % a[i];
  }

  cout << sum << endl;

}
