#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base ::sync_with_stdio(false);
  cin.tie(0);
  int n, best = 0, x, sum = 0;
  cin >> n;
  while (n--) {
    cin >> x;
    sum += x;
    best = max(best, x);
  }
  sum -= best;
  cout << best - sum + 1 << '\n';
  return 0;
}
