#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e4 + 5;
const int mod = 1e9 + 7;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int n;
  cin >> n;
  int a[n + 5], mx = 0;
  long long sum = 0;
  for (int i = 0; i < n; i++) cin >> a[i], sum += a[i], mx = max(mx, a[i]);
  sum -= mx;
  cout << (mx - sum + 1) << endl;
  return 0;
}
