#include<iostream>
using namespace std;

int main() {
  int N;
  cin >> N;
  vector<int> vec(N);
  for(int i = 0;i < N;i++) {
    cin >> vec.at(i);
  }
  int count = 1;
  for(int j = 0;j < N;j++) {
    count = count * vec.at(i);
  }
  count = count - 1;
  int answer = 0;
  for(int k = 0;k  N;k++) {
    answer = answer + count % vec.at(k)
  }
  cout << answer << endl;
}