#include <bits/stdc++.h>
int ctoi(const char c) {
  if ('0' <= c && c <= '9') return (c - '0');
  return -1;
}
using namespace std;
using pii = pair<int, int>;
long long gcd(long long a, long long b) { return (b == 0 ? a : gcd(b, a % b)); }
long long lcm(long long a, long long b) { return a * b / gcd(a, b); }
int main() {
  long long A, B;
  cin >> A;
  B = -A;
  for (int i = 0; i < (A); i++) {
    cin >> A;
    B += A;
  }
  cout << B << endl;
}
