#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  int n;
  cin >> n;
  int arr[n];
  for (int i = 0; i < n; i++) cin >> arr[i];
  sort(arr, arr + n);
  long long s = accumulate(arr, arr + n - 1, 0ll);
  cout << max(1ll, arr[n - 1] + 1 - s);
  return 0;
}
