#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, x = 0, y = 0;
  cin >> n;
  int *mas = new int[n];
  for (int i = 0; i < n; i++) cin >> mas[i];
  int max = mas[0], k = 0;
  for (int i = 1; i < n; i++) {
    if (mas[i] > max) {
      max = mas[i];
      k = i;
    }
  }
  int rez = max + 1;
  for (int i = 0; i < n; i++) {
    if (i != k) rez = rez - mas[i];
  }
  cout << rez;
  return 0;
}
